ORCID Profile
0000-0003-3405-3517
Current Organisations
University of Aberdeen School of Medicine Medical Sciences and Nutrition
,
University of Aberdeen
,
NHS Grampian
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Publications
Exact exchange and the density functional theory of metal-to-ligand charge-transfer in fac-Ir(ppy)3
Publisher: Elsevier BV
Date: 06-2016
Large area monolithic organic solar cells
Publisher: SPIE
Date: 27-11-2012
DOI: 10.1117/12.999270
Relating Structure to Efficiency in Surfactant-Free Polymer/Fullerene Nanoparticle-Based Organic Solar Cells
Publisher: American Chemical Society (ACS)
Date: 28-11-2017
Abstract: Nanoparticle dispersions open up an ecofriendly route toward printable organic solar cells. They can be formed from a variety of organic semiconductors by using miniemulsions that employ surfactants to stabilize the nanoparticles in dispersion and to prevent aggregation. However, whenever surfactant-based nanoparticle dispersions have been used to fabricate solar cells, the reported performances remain moderate. In contrast, solar cells from nanoparticle dispersions formed by precipitation (without surfactants) can exhibit power conversion efficiencies close to those of state-of-the-art solar cells processed from blend solutions using chlorinated solvents. In this work, we use small-angle neutron scattering measurements and transient absorption spectroscopy to investigate why surfactant-free nanoparticles give rise to efficient organic solar cells. We show that surfactant-free nanoparticles comprise a uniform distribution of small semiconductor domains, similar to that of bulk-heterojunction films formed using traditional solvent processing. This observation differs from surfactant-based miniemulsion nanoparticles that typically exhibit core-shell structures. Hence, the surfactant-free nanoparticles already possess the optimum morphology for efficient energy conversion before they are assembled into the photoactive layer of a solar cell. This structural property underpins the superior performance of the solar cells containing surfactant-free nanoparticles and is an important design criterion for future nanoparticle inks.
Revealing the Interplay between Charge Transport, Luminescence Efficiency, and Morphology in Organic Light‐Emitting Diode Blends
Publisher: Wiley
Date: 23-12-2019
Synthesis of a porphyrin/conjugated polymer hybrid
Publisher: Elsevier BV
Date: 06-1999
Carbohydrate globules: molecular asterisk-cored dendrimers for carbohydrate presentation
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3PY01123B
Interface Engineering of Solution-Processed Hybrid Organohalide Perovskite Solar Cells
Publisher: American Chemical Society (ACS)
Date: 06-2018
Abstract: Engineering the interface between the perovskite absorber and the charge-transporting layers has become an important method for improving the charge extraction and open-circuit voltage ( V
The impact of hot charge carrier mobility on photocurrent losses in polymer-based solar cells
Publisher: Springer Science and Business Media LLC
Date: 22-07-2014
DOI: 10.1038/SREP05695
Porphyrins with appended phenanthroline units: a means by which porphyrin π-systems can be connected to an external redox centre
Publisher: Royal Society of Chemistry (RSC)
Date: 1995
DOI: 10.1039/C39950001921
Clustering of High Molecular Weight PCDTBT in Bulk-Heterojunction Casting Solutions
Publisher: American Chemical Society (ACS)
Date: 12-11-2015
The synthesis and properties of solution processable red-emitting phosphorescent dendrimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B400160E
High‐Performance, Solution‐Processed Non‐polymeric Organic Photodiodes
Publisher: Wiley
Date: 29-09-2014
Next-generation applications for integrated perovskite solar cells
Publisher: Springer Science and Business Media LLC
Date: 05-01-2023
DOI: 10.1038/S43246-022-00325-4
Abstract: Organic/inorganic metal halide perovskites attract substantial attention as key materials for next-generation photovoltaic technologies due to their potential for low cost, high performance, and solution processability. The unique properties of perovskites and the rapid advances that have been made in solar cell performance have facilitated their integration into a broad range of practical applications, including tandem solar cells, building-integrated photovoltaics, space applications, integration with batteries and supercapacitors for energy storage systems, and photovoltaic-driven catalysis. In this Review, we outline notable achievements that have been made in these photovoltaic-integrated technologies. Outstanding challenges and future perspectives for the development of these fields and potential next-generation applications are discussed.
Phosphorescent Light‐Emitting Transistors: Harvesting Triplet Excitons
Publisher: Wiley
Date: 21-12-2009
Abstract: Phosphorescent light-emitting transistors, in which light emission from singlet and triplet energy levels is harvested using solution-processed materials, are presented. While a green phosphorescent dendrimer exhibits an external quantum efficiency of 0.45% at 480 cd m(-2) , a red polymer hosphorescent small-molecule blend produces a brightness exceeding 30 cd m(-2) with a relatively high hole mobility of 2.5 × 10(-2) cm(2) V(-1) s(-1) .
The binding and fluorescence quenching efficiency of nitroaromatic (explosive) vapors in fluorescent carbazole dendrimer thin films
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CP51372F
Abstract: We present a study on three generations of fluorescent carbazole dendrimers that exhibit strong binding with nitroaromatic compounds accompanied by photoluminescence (PL) quenching, making them attractive sensing materials for the detection of explosives such as 2,4,6-trinitrotoluene (TNT). The absorption and release of vapors of the (deuterated) TNT analogue 4-nitrotoluene (pNT) from thin films of the dendrimers were studied with a combination of time-correlated neutron reflectometry and PL spectroscopy. When saturated with pNT the PL of the films was fully quenched and could not be recovered with flowing nitrogen at room temperature but only upon heating to 40-80 °C. Although the majority of the absorbed pNT could be removed with this method the recovered films were found to still contain a residual pNT concentration of ~0.1 molecules per cubic nanometer. However, the proportion of the PL recovered increased with generation with the third generation dendrimer exhibiting close to full recovery despite the presence of residual pNT. This result is attributed to a combination of two effects. First, the dendrimer films present a range of binding sites for nitroaromatic molecules with the stronger binding sites surviving the thermal recovery process. Second, there is a large decrease of the exciton diffusion coefficient with dendrimer generation, preventing migration of the excitation to the remaining bound pNT.
In-plane superfluid density and microwave conductivity of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for d-wave pairing and resilient quasiparticles
Publisher: American Physical Society (APS)
Date: 07-08-2013
Effect of Surface Roughness on Light-Absorber Orientation in an Organic Photovoltaic Film
Publisher: American Chemical Society (ACS)
Date: 10-07-2019
Improved stability of non-ITO stacked electrodes for large area flexible organic solar cells
Publisher: Elsevier BV
Date: 11-2014
Bulk heterojunction thickness uniformity – a limiting factor in large area organic solar cells?
Publisher: Wiley
Date: 07-2015
Impact of Dimerization on Phase Separation and Crystallinity in Bulk Heterojunction Films Containing Non-Fullerene Acceptors
Publisher: American Chemical Society (ACS)
Date: 06-06-2016
Fluorinated Interlayer Modulation of NiOx-Based Inverted Perovskite Solar Cells
Publisher: American Chemical Society (ACS)
Date: 09-09-2022
Abstract: p-Type inorganic nickel oxide (NiOx) exhibits high transparency, tunable-optoelectronic properties, and a work function (
Atomically Doped 2D Black Phosphorus for Efficient and Stable Perovskite Solar Cells
Publisher: Wiley
Date: 17-10-2023
Doping‐Induced Screening of the Built‐in‐Field in Organic Solar Cells: Effect on Charge Transport and Recombination
Publisher: Wiley
Date: 10-2012
Efficient, Large Area, and Thick Junction Polymer Solar Cells with Balanced Mobilities and Low Defect Densities
Publisher: Wiley
Date: 29-09-2014
Relativistic effects in a phosphorescent Ir(III) complex
Publisher: American Physical Society (APS)
Date: 21-01-2011
Solution-processed non-polymeric organic photodiodes
Publisher: SPIE
Date: 31-08-2015
DOI: 10.1117/12.2187583
Energetic requirements of iridium(iii ) complex based photosensitisers in photocatalytic hydrogen generation
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP02997F
Abstract: Hydrogen generation is observed when excited Ir( iii ) complexes (PS*) are reduced by the sacrificial agent (SA), which occurs when E (PS*/PS − ) and E (SA + /SA) is .2 V.
Photophysics of detection of explosive vapours via luminescence quenching of thin films: impact of inter-molecular interactions
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP04536G
Abstract: Fluorescence-based detection of explosive analytes requires an understanding of the nature of the excited state responsible for the luminescence response of a sensing material.
Properties of Dual Emissive Dendrimers Based on ThermallyActivated Delayed Fluorescence Dendrons and a Phosphorescent Ir(ppy)3 Core
Publisher: Wiley
Date: 07-07-2022
Abstract: Dual emission light‐emitting dendrimers composed of phosphorescent fac ‐tris[2‐phenylpyridyl]iridium(III) [Ir(ppy) 3 ] cores and thermally activated delayed fluorescence‐based (TADF‐based) dendrons have been prepared. The TADF‐based dendrons are designed to have green or blue emission. The dendrimers show solvatochromism, with the emission switching between phosphorescence and TADF depending on the medium in which the measurement is undertaken. Time‐dependent photoluminescence (PL) spectra measurements show that the TADF dendrons can act as an energy pool for emission from the phosphorescent core. The PL quantum yields (PLQYs) are found to be strongly dependent on the dielectric constant of the solvent, ranging from as high as 76% to as low as 0.3%. Neat films of the dendrimers are found to have relatively balanced hole and electron mobilities of order 10 –6 cm 2 V –1 s –1 , with bilayer organic light‐emitting diodes (OLEDs) containing neat emissive layers having a maximum external quantum efficiency ( EQE ) of 4.7% for a film having a PLQY of 12%. Finally, the solution processed OLEDs fabricated using 0.4 mol% of the dendrimers blended with 9‐[3‐(9 H ‐carbazol‐9‐yl)phenyl]‐9 H ‐carbazole‐3‐carbonitrile result in green emission with maximum EQEs of 9.8% and 15.1% for the dendrimers with green and blue emissive TADF dendrons, respectively.
Photocarrier drift distance in organic solar cells and photodetectors
Publisher: Springer Science and Business Media LLC
Date: 28-04-2015
DOI: 10.1038/SREP09949
Abstract: Light harvesting systems based upon disordered materials are not only widespread innature, but are also increasingly prevalent in solar cells and photodetectors.Ex les include organic semiconductors, which typically possess low charge carriermobilities and Langevin-type recombination dynamics – both of whichnegatively impact the device performance. It is accepted wisdom that the“drift distance” (i.e., the distance a photocarrier driftsbefore recombination) is defined by the mobility-lifetime product in solar cells. Wedemonstrate that this traditional figure of merit is inadequate for describing thecharge transport physics of organic light harvesting systems. It is experimentallyshown that the onset of the photocarrier recombination is determined by theelectrode charge and we propose the mobility-recombination coefficient product as analternative figure of merit. The implications of these findings are relevant to awide range of light harvesting systems and will necessitate a rethink of thecritical parameters of charge transport.
Solid-State Dendrimer Sensors: Probing the Diffusion of an Explosive Analogue Using Neutron Reflectometry
Publisher: American Chemical Society (ACS)
Date: 17-07-2009
DOI: 10.1021/LA9017689
Abstract: Determining how analytes are sequestered into thin films is important for solid-state sensors that detect the presence of the analyte by oxidative luminescence quenching. We show that thin (230 +/- 30 A) and thick (750 +/- 50 A) films of a first-generation dendrimer comprised of 2-ethylhexyloxy surface groups, biphenyl-based dendrons, and a 9,9,9',9'-tetra-n-propyl-2,2'-bifluorene core, can rapidly and reversibly detect p-nitrotoluene by oxidative luminescence quenching. For both the thin and thick films the photoluminescence (PL) is quenched by p-nitrotoluene by approximately 90% in 4 s, which is much faster than that reported for luminescent polymer films. Combined PL and neutron reflectometry measurements on pristine and analyte-saturated films gave important insight into the analyte adsorption process. It was found that during the adsorption process the films swelled, being on average 4% thicker for both the thin and thick dendrimer films. At the same time the PL was completely quenched. On removal of the analyte the films returned to their original thickness and scattering length density, and the PL was restored, showing that the sensing process was fully reversible.
Efficient solution-processed dendrimer OLEDs
Publisher: SPIE
Date: 16-09-2002
DOI: 10.1117/12.483063
Superconductivity suppression and peak resistivity enhancement for thin crystals of κ‐(BEDT‐TTF)2Cu(SCN)2
Publisher: Wiley
Date: 22-03-2012
Investigating charge generation in polymer:non-fullerene acceptor bulk heterojunction films
Publisher: Elsevier BV
Date: 04-2018
Identifying the optimum composition in organic solar cells comprising non-fullerene electron acceptors
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TA10554G
Mixed Domains Enhance Charge Generation and Extraction in Bulk-Heterojunction Solar Cells with Small-Molecule Donors
Publisher: Wiley
Date: 24-03-2018
The effect of fluorination on the low and high frequency dielectric constants of non-polymeric organic semiconductors – towards homojunction solar cells
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TC02740F
Blue Phosphorescence from Iridium(III) Complexes at Room Temperature
Publisher: American Chemical Society (ACS)
Date: 26-09-2006
DOI: 10.1021/CM061173B
A green-absorbing dendrimer based photodetector for image sensing applications
Publisher: SPIE
Date: 19-08-2010
DOI: 10.1117/12.867735
Development of Dendrimers: Macromolecules for Use in Organic Light-Emitting Diodes and Solar Cells
Publisher: American Chemical Society (ACS)
Date: 27-03-2007
DOI: 10.1021/CR050136L
Defect/Interface Recombination Limited Quasi-Fermi Level Splitting and Open-Circuit Voltage in Mono- and Triple-Cation Perovskite Solar Cells
Publisher: American Chemical Society (ACS)
Date: 17-07-2020
Highly efficient solution‐processible phosphorescent dendrimers for organic light‐emitting diodes
Publisher: Wiley
Date: 03-2003
DOI: 10.1889/1.1831700
A Light-Blue Phosphorescent Dendrimer for Efficient Solution-Processed Light-Emitting Diodes
Publisher: Wiley
Date: 09-2005
Efficient, Large Area ITO‐and‐PEDOT‐free Organic Solar Cell Sub‐modules
Publisher: Wiley
Date: 10-04-2012
Thiophene dendrimer-based low donor content solar cells
Publisher: AIP Publishing
Date: 05-09-2016
DOI: 10.1063/1.4961935
Abstract: Low donor content solar cells containing polymeric and non-polymeric donors blended with fullerenes have been reported to give rise to efficient devices. In this letter, we report that a dendrimeric donor can also be used in solution-processed low donor content devices when blended with a fullerene. A third generation dendrimer containing 42 thiophene units (42T) was found to give power conversion efficiencies of up to 3.5% when blended with PC70BM in optimized devices. The best efficiency was measured with 10 mole percent (mol. %) of 42T in PC70BM and X-ray reflectometry showed that the blends were uniform. Importantly, while 42T comprised 10 mol. % of the film, it made up 31% of the film by volume. Finally, it was found that solvent annealing was required to achieve the largest open circuit voltage and highest device efficiencies.
Twisted dendrons for highly luminescent green emissive phosphorescent dendrimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TC03491E
Abstract: A new class of twisted rigid biphenyl-based dendrons with t -butyl surface groups have been prepared and attached to a green emissive fac -tris(2-phenylpyridyl)iridium( iii ) core.
Effect of dendrimer surface groups on the properties of phosphorescent emissive films
Publisher: Elsevier BV
Date: 12-2021
Investigating Morphology and Stability of Fac‐tris (2‐phenylpyridyl)iridium(III) Films for OLEDs
Publisher: Wiley
Date: 25-03-2011
Highly efficient single-layer dendrimer light-emitting diodes with balanced charge transport
Publisher: AIP Publishing
Date: 24-06-2003
DOI: 10.1063/1.1586999
Abstract: High-efficiency single-layer-solution-processed green light-emitting diodes based on a phosphorescent dendrimer are demonstrated. A peak external quantum efficiency of 10.4% (35 cd/A) was measured for a first generation fac-tris(2-phenylpyridine) iridium cored dendrimer when blended with 4,4′-bis(N-carbazolyl)biphenyl and electron transporting 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene at 8.1 V. A maximum power efficiency of 12.8 lm/W was measured also at 8.1 V and 550 cd/m2. These results indicate that, by simple blending of bipolar and electron-transporting molecules, highly efficient light-emitting diodes can be made employing a very simple device structure.
Investigating the donor:acceptor ratio in thermally activated delayed fluorescence light-emitting macromolecules
Publisher: Elsevier BV
Date: 06-2022
Time-independent charge carrier mobility in a model polymer:fullerene organic solar cell
Publisher: Elsevier BV
Date: 2015
Understanding charge transport in Ir(ppy)3:CBP OLED films
Publisher: AIP Publishing
Date: 06-03-2019
DOI: 10.1063/1.5083639
Abstract: Ir(ppy)3:CBP blends have been widely studied as the emissive layer in organic light emitting diodes (OLEDs), yet crucial questions about charge transport within the layer remain unaddressed. Recent molecular dynamics simulations show that the Ir(ppy)3 molecules are not isolated from each other, but at concentrations of as low as 5 wt. % can be part of connected pathways. Such connectivity raises the question of how the iridium(iii) complexes contribute to long-range charge transport in the blend. We implement a kinetic Monte Carlo transport model to probe the guest concentration dependence of charge mobility and show that distinct minima appear at approximately 10 wt. % Ir(ppy)3 due to an increased number of trap states that can include interconnected complexes within the blend film. The depth of the minima is shown to be dependent on the electric field and to vary between electrons and holes due to their different trapping depths arising from the different ionization potentials and electron affinities of the guest and host molecules. Typical guest-host OLEDs use a guest concentration below 10 wt. % to avoid triplet-triplet annihilation, so these results suggest that optimal device performance is achieved when there is significant charge trapping on the iridium(iii) complex guest molecules and minimum interactions of the emissive chromophores that can lead to triplet-triplet annihilation.
Unraveling exciton processes in Ir(ppy)3:CBP OLED films upon photoexcitation
Publisher: AIP Publishing
Date: 22-04-2021
DOI: 10.1063/5.0044177
Abstract: Emissive layers in phosphorescent organic light-emitting diodes commonly make use of guest–host blends such as Ir(ppy)3:CBP to achieve high external quantum efficiencies. However, while the Ir(ppy)3:CBP blend has been studied experimentally, crucial questions remain regarding how exciton diffusion is dependent on the distribution of the guest in the host, which can currently only be addressed at the atomic level via computational modeling. In this work, kinetic Monte Carlo simulations are utilized to gain insight into exciton diffusion in Ir(ppy)3:CBP blend films. The effects of both guest concentration and exciton density on various system properties are analyzed, including the probability of singlet excitons being converted to triplets, and the probability of those triplets decaying radiatively. Significantly, these simulations suggest that triplet diffusion occurs almost exclusively via guest–guest Dexter transfer and that concentration quenching of triplets induced by guest–guest intermolecular dipole-dipole interactions has a negligible effect at high exciton densities due to the prevalence of triplet–triplet annihilation. Furthermore, results for vacuum deposited morphologies derived from molecular dynamics simulations are compared to the results obtained using a simple cubic lattice approximation with randomly distributed guest molecules. We show that while differences in host-based processes such as singlet diffusion are observed, overall, the results on the fate of the excitons are in good agreement for the two morphology types, particularly for guest-based processes at low guest concentrations where guest clustering is limited.
Effect of Dimensionality in Dendrimeric and Polymeric Fluorescent Materials for Detecting Explosives
Publisher: American Chemical Society (ACS)
Date: 02-12-2010
DOI: 10.1021/MA102369Q
Solution-processed pentathiophene dendrimer based photodetectors for digital cameras
Publisher: Elsevier BV
Date: 06-2014
9,9′-Bifluorenylidene-diketopyrrolopyrrole donors for non-polymeric solution processed solar cells
Publisher: Elsevier BV
Date: 04-2019
The synthesis and ring-opening metathesis polymerization of glycomonomers
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5RA25732H
Abstract: The synthesis of a series of short poly(norbornene)s displaying pendant disaccharides is reported.
The Development of Light-Emitting Dendrimers for Displays
Publisher: Wiley
Date: 02-07-2007
Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real-Time Sensing
Publisher: Wiley
Date: 09-2016
Abstract: Time-resolved quartz crystal microbalance with in situ fluorescence measurements are used to monitor the sorption of the nitroaromatic (explosive) vapor, 2,4-dinitrotoluene (DNT) into a porous pentiptycene-containing poly(phenyleneethynylene) sensing film. Correlation of the nitroaromatic mass uptake with fluorescence quenching shows that the analyte diffusion follows the Case-II transport model, a film-swelling-limited process, in which a sharp diffusional front propagates at a constant velocity through the film. At a low vapor pressure of DNT of ≈16 ppb, the analyte concentration in the front is sufficiently high to give an average fluorophore-analyte separation of ≈1.5 nm. Hence, a long exciton diffusion length is not required for real-time sensing in the solid state. Rather the diffusion behavior of the analyte and the strength of the binding interaction between the analyte and the polymer play first-order roles in the fluorescence quenching process.
Effect of dendrimer generation and surface groups on the optoelectronic properties of green emitting bis-tridentate iridium(iii ) complexes designed for OLEDs
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TC01798B
Additions and corrections for Journal of Materials Chemistry C published 12th March 2014 to 25th June 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 31-07-2014
DOI: 10.1039/C4TC90093F
Challenges in Fluorescence Detection of Chemical Warfare Agent Vapors Using Solid‐State Films
Publisher: Wiley
Date: 06-11-2020
Abstract: Organophosphorus (OP)-based nerve agents are extremely toxic and potent acetylcholinesterase inhibitors and recent attacks involving nerve agents highlight the need for fast detection and intervention. Fluorescence-based detection, where the sensing material undergoes a chemical reaction with the agent causing a measurable change in the luminescence, is one method for sensing and identifying nerve agents. Most studies use the simulants diethylchlorophosphate and di-iso-propylfluorophosphate to evaluate the performance of sensors due to their reduced toxicity relative to OP nerve agents. While detection of nerve agent simulants in solution is relatively widely reported, there are fewer reports on vapor detection using solid-state sensors. Herein, progress in organic semiconductor sensing materials developed for solid-state detection of OP-based nerve agent vapors is reviewed. The effect of acid impurities arising from the hydrolysis of simulants and nerve agents on the efficacy and selectivity of the reported sensing materials is also discussed. Indeed, in some cases it is unclear whether it is the simulant that is detected or the acid hydrolysis products. Finally, it is highlighted that while analyte diffusion into the sensing film is critical in the design of fast, responsive sensing systems, it is an area that is currently not well studied.
Analysis of the emitting states of an Ir(III) complex with strong blue emission
Publisher: Elsevier BV
Date: 11-2015
Acid is a potential interferent in fluorescent sensing of chemical warfare agent vapors
Publisher: Springer Science and Business Media LLC
Date: 26-03-2021
DOI: 10.1038/S42004-021-00482-6
Abstract: A common feature of fluorescent sensing materials for detecting chemical warfare agents (CWAs) and simulants is the presence of nitrogen-based groups designed to nucleophilically displace a phosphorus atom substituent, with the reaction causing a measurable fluorescence change. However, such groups are also basic and so sensitive to acid. In this study we show it is critical to disentangle the response of a candidate sensing material to acid and CWA simulant. We report that pyridyl-containing sensing materials designed to react with a CWA gave a strong and rapid increase in fluorescence when exposed to Sarin, which is known to contain hydrofluoric acid. However, when tested against acid-free diethylchlorophosphate and di- iso -propylfluorophosphate, simulants typically used for evaluating novel G-series CWA sensors, there was no change in the fluorescence. In contrast, simulants that had been stored or tested under a standard laboratory conditions all led to strong changes in fluorescence, due to acid impurities. Thus the results provide strong evidence that care needs to be taken when interpreting the results of fluorescence-based solid-state sensing studies of G-series CWAs and their simulants. There are also implications for the application of these pyridyl-based fluorescence and other nucleophilic/basic sensing systems to real-world CWA detection.
High-Mobility, Heterostructure Light-Emitting Transistors and Complementary Inverters
Publisher: American Chemical Society (ACS)
Date: 10-2014
DOI: 10.1021/PH500300N
An approach to porphyrin-based molecular wires: Synthesis of a bis(porphyrin)tetraone and its conversion to a linearly conjugated tetrakisporphyrin system
Publisher: Royal Society of Chemistry (RSC)
Date: 1991
DOI: 10.1039/C39910001569
The effect of dendronisation of arylamine centred chromophores on field effect transistor performance
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0PY00083C
Morphology of a Bulk Heterojunction Photovoltaic Cell with Low Donor Concentration
Publisher: American Chemical Society (ACS)
Date: 28-08-2018
Abstract: Atomistic nonequilibrium molecular dynamics simulations have been used to model the morphology of small-molecule bulk heterojunction films formed by vapor deposition as used in organic photovoltaics. Films comprising C
A rapid route to carbazole containing dendrons and phosphorescent dendrimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B717750J
Controlling hierarchy in solution-processed polymer solar cells based on crosslinked P3HT
Publisher: Wiley
Date: 07-08-2013
Slower carriers limit charge generation in organic semiconductor light-harvesting systems
Publisher: Springer Science and Business Media LLC
Date: 21-06-2016
DOI: 10.1038/NCOMMS11944
Abstract: Blends of electron-donating and -accepting organic semiconductors are widely used as photoactive materials in next-generation solar cells and photodetectors. The yield of free charges in these systems is often determined by the separation of interfacial electron–hole pairs, which is expected to depend on the ability of the faster carrier to escape the Coulomb potential. Here we show, by measuring geminate and non-geminate losses and key transport parameters in a series of bulk-heterojunction solar cells, that the charge-generation yield increases with increasing slower carrier mobility. This is in direct contrast with the well-established Braun model where the dissociation rate is proportional to the mobility sum, and recent models that underscore the importance of fullerene aggregation for coherent electron propagation. The behaviour is attributed to the restriction of opposite charges to different phases, and to an entropic contribution that favours the joint separation of both charge carriers.
Room-temperature tilted-target sputtering deposition of highly transparent and low sheet resistance Al doped ZnO electrodes
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TC00695C
Abstract: OPV devices comprised of AZO electrodes with sheet resistances of Ω □ −1 and transmittance in the visible region up to an average of 84% showed comparable performance to devices with a transparent ITO electrode.
Dicyanovinyl-based fluorescent sensors for dual mechanism amine sensing
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TC03974H
Abstract: We report two dual mechanism fluorescent sensors that enable selective sensing of alkyl primary amines with a low detection limit.
77‐2: Invited Paper: Probing the Thermal Stability of OLEDs with Neutrons
Publisher: Wiley
Date: 05-2017
DOI: 10.1002/SDTP.11839
High mobility solution-processed hybrid light emitting transistors
Publisher: AIP Publishing
Date: 03-11-2014
DOI: 10.1063/1.4900933
A new method for the synthesis of porphyrin-α-diones that is applicable to the synthesis of trans-annular extended porphyrin systems
Publisher: Royal Society of Chemistry (RSC)
Date: 1991
DOI: 10.1039/C39910001567
Tuning the optoelectronic properties of cyanine and ketocyanine dyes by incorporation of 9,9-di-n-propylfluorenylindolenine
Publisher: Elsevier BV
Date: 02-2014
Explosive Sensing with Fluorescent Dendrimers: The Role of Collisional Quenching
Publisher: American Chemical Society (ACS)
Date: 14-09-2010
DOI: 10.1021/CM1020355
Pyrrolo[3,2-b]pyrrole-1,4-dione (IsoDPP) end capped with napthalimide or phthalimide
Publisher: MDPI AG
Date: 14-10-2020
DOI: 10.3390/MOLECULES25204700
Abstract: We introduce two novel solution-processable electron acceptors based on an isomeric core of the much explored diketopyrrolopyrrole (DPP) moiety, namely pyrrolo[3,2-b]pyrrole-1,4-dione (IsoDPP). The newly designed and synthesized compounds, 6,6′-[(1,4-bis{4-decylphenyl}-2,5-dioxo-1,2,4,5-tetrahydropyrrolo[3,2-b]pyrrole-3,6-diyl)bis(thiophene-5,2-diyl)]bis[2-(2-butyloctyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione] (NAI-IsoDPP-NAI) and 5,5′-[(1,4-bis{4-decylphenyl}-2,5-dioxo-1,2,4,5-tetrahydropyrrolo[3,2-b]pyrrole-3,6-diyl)bis(thiophene-5,2-diyl)]bis[2-(2-butyloctyl)isoindoline-1,3-dione] (PI-IsoDPP-PI) have been synthesized via Suzuki couplings using IsoDPP as a central building block and napthalimide or phthalimide as end-capping groups. The materials both exhibit good solubility in a wide range of organic solvents including chloroform (CF), dichloromethane (DCM), and tetrahydrofuran (THF), and have a high thermal stability. The new materials absorb in the wavelength range of 300–600 nm and both compounds have similar electron affinities, with the electron affinities that are compatible with their use as acceptors in donor-acceptor bulk heterojunction (BHJ) organic solar cells. BHJ devices comprising the NAI-IsoDPP-NAI acceptor with poly(3-n-hexylthiophene) (P3HT) as the donor were found to have a better performance than the PI-IsoDPP-PI containing cells, with the best device having a VOC of 0.92 V, a JSC of 1.7 mAcm−2, a FF of 63%, and a PCE of 0.97%.
Fluorescent sensors for the detection of free-base illicit drugs - effect of tuning the electronic properties
Publisher: Elsevier BV
Date: 07-2023
Regiospecific introduction of four substituents to porphyrin systems at antipodal pyrrolenic positions
Publisher: Royal Society of Chemistry (RSC)
Date: 1991
DOI: 10.1039/C39910001564
Effect of dendron structure on the luminescent and charge transporting properties of solution processed dendrimer-based OLEDs
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TC03949K
Abstract: The energy transfer, PLQY, charge mobility, and OLED performance of blend films of first generation Ir(ppy) 3 -cored light-emitting dendrimers and dendrimeric TCTA-based hosts are found to be dependent on the dendrons and surface groups used.
Effect of PEDOT:PSS on the performance of solution-processed blue phosphorescent organic light-emitting diodes with an exciplex host
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1MA00729G
Abstract: The acidity of the PEDOT:PSS hole injection layer was found to effect the performance of efficient solution-processed organic light-emitting diodes incorporating a light-emitting layer composed of a blue phosphorescent dendrimer:exciplex host blend.
Elucidating the effects of guest-host energy level alignment on charge transport in phosphorescent OLEDs
Publisher: AIP Publishing
Date: 23-12-2019
DOI: 10.1063/1.5131680
Abstract: The correct choice of guest and host molecules in the light-emitting layer is essential for developing high performance phosphorescent organic light emitting devices. However, the effects of the energy level alignment between the guest and the host are yet to be fully elucidated. In this Letter, we use kinetic Monte Carlo simulations to investigate guest-host systems in which the energy gap of the guest and host is fixed, and only the relative energies of the ionization potential/electron affinity are changed to elucidate their effect on charge transport. It was determined that the mobility balance in the blend was sensitive to the energy level alignment, allowing balanced active layer mobility to be achieved despite the hole and electron mobilities being different by around one order of magnitude. It was also found that the mobility of the faster carrier was more sensitive to the energy level alignment than that of the slower carrier due to reduced slower carrier thermalization under deep charge trapping on the guest.
Dendrimers for photon harvesting in organic and organic/inorganic hybrid solar cells
Publisher: SPIE
Date: 20-08-2009
DOI: 10.1117/12.825689
Nano-structured organic-metal interface for high efficiency organic solar cells
Publisher: IEEE
Date: 08-2011
Vertical morphology in solution-processed organic solar cells
Publisher: IEEE
Date: 08-2011
Defining the light emitting area for displays in the unipolar regime of highly efficient light emitting transistors
Publisher: Springer Science and Business Media LLC
Date: 06-03-2015
DOI: 10.1038/SREP08818
Abstract: Light-emitting field effect transistors (LEFETs) are an emerging class of multifunctional optoelectronic devices. It combines the light emitting function of an OLED with the switching function of a transistor in a single device architecture. The dual functionality of LEFETs has the potential applications in active matrix displays. However, the key problem of existing LEFETs thus far has been their low EQEs at high brightness, poor ON/OFF and poorly defined light emitting area - a thin emissive zone at the edge of the electrodes. Here we report heterostructure LEFETs based on solution processed unipolar charge transport and an emissive polymer that have an EQE of up to 1% at a brightness of 1350 cd/m 2 , ON/OFF ratio 10 4 and a well-defined light emitting zone suitable for display pixel design. We show that a non-planar hole-injecting electrode combined with a semi-transparent electron-injecting electrode enables to achieve high EQE at high brightness and high ON/OFF ratio. Furthermore, we demonstrate that heterostructure LEFETs have a better frequency response ( f cut-off = 2.6 kHz ) compared to single layer LEFETs. The results presented here therefore are a major step along the pathway towards the realization of LEFETs for display applications.
Organic light-emitting diodes comprising highly luminescent red-emitting dendrimers with carbazole-based dendrons
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8TC05703F
Abstract: OLEDs containing a red emitting dendrimer with a solution PLQY of 86 ± 9% have an EQE of 12% and CIE co-ordinates of (0.65, 0.34).
High power efficiency phosphorescent poly(dendrimer) OLEDs
Publisher: The Optical Society
Date: 23-01-2012
DOI: 10.1364/OE.20.00A213
Efficient Phosphorescence by Reducing Intrachain Chromophore Interactions in Dendrimer-Containing Polymers
Publisher: American Chemical Society (ACS)
Date: 08-12-2011
DOI: 10.1021/JP2043703
Correction: The synthesis and ring-opening metathesis polymerization of glycomonomers (RSC Adv. (2016) 6 (31256-31264))
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA90037B
Abstract: Correction for ‘The synthesis and ring-opening metathesis polymerization of glycomonomers’ by Lucy G. Weaver et al. , RSC Adv. , 2016, 6 , 31256–31264.
Morphology of All-Solution-Processed "Bilayer" Organic Solar Cells
Publisher: Wiley
Date: 09-12-2011
Charge transport in highly efficient iridium cored electrophosphorescent dendrimers
Publisher: AIP Publishing
Date: 29-12-2003
DOI: 10.1063/1.1633336
Abstract: Electrophosphorescent dendrimers are promising materials for highly efficient light-emitting diodes. They consist of a phosphorescent core onto which dendritic groups are attached. Here, we present an investigation into the optical and electronic properties of highly efficient phosphorescent dendrimers. The effect of dendrimer structure on charge transport and optical properties is studied using temperature-dependent charge-generation-layer time-of-flight measurements and current voltage (I–V) analysis. A model is used to explain trends seen in the I–V characteristics. We demonstrate that fine tuning the mobility by chemical structure is possible in these dendrimers and show that this can lead to highly efficient bilayer dendrimer light-emitting diodes with neat emissive layers. Power efficiencies of 20 lm/W were measured for devices containing a second-generation (G2) Ir(ppy)3 dendrimer with a 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene electron transport layer.
A study on the preparation and photophysical properties of an iridium(iii) complexed homopolymer
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B902374G
Electric Field and Mobility Dependent First-Order Recombination Losses in Organic Solar Cells
Publisher: Wiley
Date: 07-11-2017
Efficient and bright polymer light emitting field effect transistors
Publisher: Elsevier BV
Date: 02-2015
67.1: Invited Paper: Dendrimers — Efficient Solution-Processed Phosphorescent OLED Materials
Publisher: Wiley
Date: 2005
DOI: 10.1889/1.2036382
Charge transport and recombination in heterostructure organic light emitting transistors
Publisher: Elsevier BV
Date: 10-2015
Conjugated dendrimers: a modular approach to materials for full-color displays
Publisher: SPIE
Date: 16-02-2004
DOI: 10.1117/12.512062
Precursor Route Poly(1,4-phenylenevinylene)-Based Interlayers for Perovskite Solar Cells
Publisher: American Chemical Society (ACS)
Date: 02-01-2020
Influence of Dopant Concentration and Steric Bulk on Interlayer Diffusion in OLEDs
Publisher: Wiley
Date: 25-10-2018
A Phosphorescent Poly(dendrimer) Containing Iridium(III) Complexes: Synthesis and Light-Emitting Properties
Publisher: American Chemical Society (ACS)
Date: 06-08-2010
DOI: 10.1021/MA101363H
Factors Influencing the Efficiency of Current Collection in Large Area, Monolithic Organic Solar Cells
Publisher: Wiley
Date: 23-07-2012
Application of an A–A′–A-Containing Acceptor Polymer in Sequentially Deposited All-Polymer Solar Cells
Publisher: American Chemical Society (ACS)
Date: 03-07-2018
Abstract: PNNT has been prepared as a polymeric electron acceptor for organic solar cells. The polymer has an A-A'-A acceptor motif linked alternatively with thiophene and vinyl moieties. The A'-unit is a naphthalene diimide, while the A groups are thiazoles. PNNT films were found to have an estimated electron affinity of ≈4.3 eV and an electron mobility of the order of 10
A Narrow Optical Gap Small Molecule Acceptor for Organic Solar Cells
Publisher: Wiley
Date: 03-09-2012
Colour selective organic photodetectors utilizing ketocyanine-cored dendrimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TC30472H
Dynamics of Charge Generation and Transport in Polymer-Fullerene Blends Elucidated Using a PhotoFET Architecture
Publisher: American Chemical Society (ACS)
Date: 21-01-2014
DOI: 10.1021/PH400047B
Ruthenium complex-cored dendrimers: Shedding light on efficiency trade-offs in dye-sensitised solar cells
Publisher: Elsevier BV
Date: 11-2009
Organic Photodiodes: The Future of Full Color Detection and Image Sensing
Publisher: Wiley
Date: 25-04-2016
Abstract: Major growth in the image sensor market is largely as a result of the expansion of digital imaging into cameras, whether stand-alone or integrated within smart cellular phones or automotive vehicles. Applications in biomedicine, education, environmental monitoring, optical communications, pharmaceutics and machine vision are also driving the development of imaging technologies. Organic photodiodes (OPDs) are now being investigated for existing imaging technologies, as their properties make them interesting candidates for these applications. OPDs offer cheaper processing methods, devices that are light, flexible and compatible with large (or small) areas, and the ability to tune the photophysical and optoelectronic properties - both at a material and device level. Although the concept of OPDs has been around for some time, it is only relatively recently that significant progress has been made, with their performance now reaching the point that they are beginning to rival their inorganic counterparts in a number of performance criteria including the linear dynamic range, detectivity, and color selectivity. This review covers the progress made in the OPD field, describing their development as well as the challenges and opportunities.
Dielectric Constant Engineering of Organic Semiconductors: Effect of Planarity and Conjugation Length
Publisher: Wiley
Date: 11-08-2022
Abstract: Bulk heterojunction organic solar cells continue to show steady photoconversion efficiency improvements. However, single component organic solar cells are a particularly attractive alternative due to the relative simplicity of device manufacture. It has been proposed that organic semiconductors with a high dielectric constant (≈10) could give rise to spontaneous free charge carrier generation upon photoexcitation. In this manuscript, factors are explored that affect the dielectric constant of organic semiconductors, particularly the optical‐frequency dielectric constant. The properties of monomers, dimers and trimers of two isoelectronic families of materials that have acceptor units composed of one or two dicyanovinylbenzothiadiazole moieties and one to three donor units are compared. The donor components are composed of either fluorenyl or cyclopentadithiophene moieties with the same glycol‐based solubilizing groups. It is found that chromophore planarity and orientation with respect to the substrate, and film density affect the optical and electronic properties of the materials, especially the high‐frequency dielectric constant. The results also indicate that delocalization of the highest occupied and lowest unoccupied molecular orbitals is a critical factor. The dimer with two dicyanovinylbenzothiadiazole moieties and two dithienocyclopentadiene units is found to have the highest optical frequency dielectric constant and overall performance.
Understanding the performance differences between solution and vacuum deposited OLEDs: A computational approach
Publisher: AIP Publishing
Date: 06-2022
DOI: 10.1063/5.0091142
Abstract: Solution-processing of organic light-emitting diode films has potential advantages in terms of cost and scalability over vacuum-deposition for large area applications. However, solution processed small molecule films can have lower overall device performance. Here, novel molecular dynamics techniques are developed to enable faster simulation of solvent evaporation that occurs during solution processing and give films of thicknesses relevant to real devices. All-atom molecular dynamics simulations are then used in combination with kinetic Monte Carlo transport modeling to examine how differences in morphology stemming from solution or vacuum film deposition affect charge transport and exciton dynamics in films consisting of light-emitting bis(2-phenylpyridine)(acetylacetonate)iridium(III) [Ir(ppy)2(acac)] guest molecules in a 4,4′-bis(N-carbazolyl)biphenyl host. While the structures of the films deposited from vacuum and solution were found to differ, critically, only minor variations in the transport properties were predicted by the simulations even if trapped solvent was present.
Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes
Publisher: Informa UK Limited
Date: 23-03-2015
Essential Emergency and Critical Care: a consensus among global clinical experts
Publisher: BMJ
Date: 09-2021
DOI: 10.1136/BMJGH-2021-006585
Abstract: Globally, critical illness results in millions of deaths every year. Although many of these deaths are potentially preventable, the basic, life-saving care of critically ill patients are often overlooked in health systems. Essential Emergency and Critical Care (EECC) has been devised as the care that should be provided to all critically ill patients in all hospitals in the world. EECC includes the effective care of low cost and low complexity for the identification and treatment of critically ill patients across all medical specialties. This study aimed to specify the content of EECC and additionally, given the surge of critical illness in the ongoing pandemic, the essential diagnosis-specific care for critically ill patients with COVID-19. In a Delphi process, consensus ( % agreement) was sought from a erse panel of global clinical experts. The panel iteratively rated proposed treatments and actions based on previous guidelines and the WHO/ICRC’s Basic Emergency Care. The output from the Delphi was adapted iteratively with specialist reviewers into a coherent and feasible package of clinical processes plus a list of hospital readiness requirements. The 269 experts in the Delphi panel had clinical experience in different acute medical specialties from 59 countries and from all resource settings. The agreed EECC package contains 40 clinical processes and 67 requirements, plus additions specific for COVID-19. The study has specified the content of care that should be provided to all critically ill patients. Implementing EECC could be an effective strategy for policy makers to reduce preventable deaths worldwide.
Comparison of the electronic properties of poly[2-(2′-ethylhexyloxy)-1,4-phenylenevinylene] prepared by different precursor polymer routes
Publisher: Royal Society of Chemistry (RSC)
Date: 1999
DOI: 10.1039/A902602I
An overview of the Australian centre for advanced photovoltaics and the Australia-us institute for advanced photovoltaics
Publisher: Springer Science and Business Media LLC
Date: 2016
DOI: 10.1557/OPL.2015.364
Abstract: The Australian Centre for Advanced Photovoltaics (ACAP) co-ordinates the activities of the six Australian research institutions and a group of industrial partners in the Australia-US Institute for Advanced Photovoltaics (AUSIAPV) to develop the next generations of photovoltaic device technology and to provide a pipeline of opportunities for performance increase and cost reduction. AUSIAPV links ACAP with US-based partners. These national and international research collaborations provide a pathway for highly visible, structured photovoltaic research collaboration between Australian and US researchers, institutes and agencies with significant joint programs based on the clear synergies between the participating organizations. The research program is organized in five collaborative Program Packages (PPs). PP1 deals with silicon wafer-based cells, focusing on three main areas: cells from solar grade silicon, rear contact and silicon-based tandem cells. PP2 involves research into a range of organic solar cells, organic/inorganic hybrid cells, "earth abundant" thin-film materials and "third generation" approaches. PP3 is concerned with optics and characterization. PP4 will deliver a substantiated methodology for assessing manufacturing costs of the different technologies and PP5 involves education, training and outreach. The main research topics, results and plans for the future are presented.
A modeling approach to understanding OLED performance improvements arising from spatial variations in guest:host blend ratio
Publisher: AIP Publishing
Date: 17-07-2023
DOI: 10.1063/5.0152922
Abstract: Phosphorescent organic light emitting diodes (OLEDs) suffer from efficiency roll off, where device efficiency rapidly decays at higher luminance. One strategy to minimize this loss of efficiency at higher luminance is the use of non-uniform or graded guest:host blend ratios within the emissive layer. This work applies a multi-scale modeling framework to elucidate the mechanisms by which a non-uniform blend ratio can change the performance of an OLED. Mobility and exciton data are extracted from a kinetic Monte–Carlo model, which is then coupled to a drift diffusion model for fast s ling of the parameter space. The model is applied to OLEDs with uniform, linear, and stepwise graduations in the blend ratio in the emissive layer. The distribution of the guests in the film was found to affect the mobility of the charge carriers, and it was determined that having a graduated guest profile broadened the recombination zone, leading to a reduction in second order annihilation rates. That is, there was a reduction in triplet–triplet and triplet-polaron annihilation. Reducing triplet–triplet and triplet-polaron annihilation would lead to an improvement in device efficiency.
Diffusion of nitroaromatic vapours into fluorescent dendrimer films for explosives detection
Publisher: Elsevier BV
Date: 04-2015
Preserving the work function of Ultra-Violet-ozone treated indium tin oxide by triarylamine-based small molecule modification for solution-processed organic light-emitting diodes with increased extern
Publisher: Elsevier BV
Date: 2021
Narrowband light detection via internal quantum efficiency manipulation of organic photodiodes
Publisher: Springer Science and Business Media LLC
Date: 27-02-2015
DOI: 10.1038/NCOMMS7343
Abstract: Spectrally selective light detection is vital for full-colour and near-infrared (NIR) imaging and machine vision. This is not possible with traditional broadband-absorbing inorganic semiconductors without input filtering, and is yet to be achieved for narrowband absorbing organic semiconductors. We demonstrate the first sub-100 nm full-width-at-half-maximum visible-blind red and NIR photodetectors with state-of-the-art performance across critical response metrics. These devices are based on organic photodiodes with optically thick junctions. Paradoxically, we use broadband-absorbing organic semiconductors and utilize the electro-optical properties of the junction to create the narrowest NIR-band photoresponses yet demonstrated. In this context, these photodiodes outperform the encumbent technology (input filtered inorganic semiconductor diodes) and emerging technologies such as narrow absorber organic semiconductors or quantum nanocrystals. The design concept allows for response tuning and is generic for other spectral windows. Furthermore, it is material-agnostic and applicable to other disordered and polycrystalline semiconductors.
Influence of the Alkyl Chain Length of (Pentafluorophenylalkyl) Ammonium Salts on Inverted Perovskite Solar Cell Performance
Publisher: American Chemical Society (ACS)
Date: 23-08-2022
Abstract: We study the effect of (2,3,4,5,6-pentafluorophenyl)alkylamine additives with differing alkyl chain lengths (methyl, ethyl, and
Correlation of diffusion and performance in sequentially processed P3HT/PCBM heterojunction films by time-resolved neutron reflectometry
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TC00063J
Assessing the sensing limits of fluorescent dendrimer thin films for the detection of explosive vapors
Publisher: Elsevier BV
Date: 02-2017
Non-radiative decay mechanisms in blue phosphorescent iridium(III) complexes
Publisher: Elsevier BV
Date: 06-2008
Correlating vapour uptake with the luminescence quenching of poly(dendrimer)s for the detection of nitro group-containing explosives
Publisher: CSIRO Publishing
Date: 06-09-2023
DOI: 10.1071/CH23131
Engineering fluorinated-cation containing inverted perovskite solar cells with an efficiency of >21% and improved stability towards humidity
Publisher: Springer Science and Business Media LLC
Date: 04-01-2021
DOI: 10.1038/S41467-020-20272-3
Abstract: Efficient and stable perovskite solar cells with a simple active layer are desirable for manufacturing. Three-dimensional perovskite solar cells are most efficient but need to have improved environmental stability. Inclusion of larger ammonium salts has led to a trade-off between improved stability and efficiency, which is attributed to the perovskite films containing a two-dimensional component. Here, we show that addition of 0.3 mole percent of a fluorinated lead salt into the three-dimensional methylammonium lead iodide perovskite enables low temperature fabrication of simple inverted solar cells with a maximum power conversion efficiency of 21.1%. The perovskite layer has no detectable two-dimensional component at salt concentrations of up to 5 mole percent. The high concentration of fluorinated material found at the film-air interface provides greater hydrophobicity, increased size and orientation of the surface perovskite crystals, and unencapsulated devices with increased stability to high humidity.
Deuteration of molecules for neutron reflectometry on organic light-emitting diode thin films
Publisher: Elsevier BV
Date: 02-2012
Extremely efficient flexible organic solar cells with a graphene transparent anode: Dependence on number of layers and doping of graphene
Publisher: Elsevier BV
Date: 2021
Quantitative real time sensing reveals enhanced sensitivity of polar dendrimer thin films for plastic explosive taggants
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TC01967B
Abstract: A method of introducing pulses of analyte vapours has been developed to study the interactions of nitro-containing analytes with fluorescent sensing films.
Elucidating the Spatial Arrangement of Emitter Molecules in Organic Light-Emitting Diode Films
Publisher: Wiley
Date: 07-02-2017
Abstract: The effect of varying the emitter concentration on the structural properties of an archetypal phosphorescent blend consisting of 4,4'-bis(N-carbazolyl)biphenyl and tris(2-phenylpyridyl)iridium(III) has been investigated using non-equilibrium molecular dynamics (MD) simulations that mimic the process of vacuum deposition. By comparison with reflectometry measurements, we show that the simulations provide an accurate model of the average density of such films. The emitter molecules were found not to be evenly distributed throughout film, but rather they can form networks that provide charge and/or energy migration pathways, even at emitter concentrations as low as ≈5 weight percent. At slightly higher concentrations, percolated networks form that span the entire system. While such networks would give improved charge transport, they could also lead to more non-radiative pathways for the emissive state and a resultant loss of efficiency.
Solid-State Fluorescence-based Sensing of TATP via Hydrogen Peroxide Detection
Publisher: American Chemical Society (ACS)
Date: 09-01-2019
DOI: 10.1021/ACSSENSORS.8B01029
Abstract: Fluorenylboronate ester chromophore-based thin films were investigated for the detection of triacetone triperoxide (TATP) vapors via the decomposition product, hydrogen peroxide. Sensing with a high level of sensitivity was achieved using a fluorescence "turn-on" mechanism based on the significant shifts in the absorption and photoluminescence spectra that occurs when the boronate esters were converted to phenoxides by hydrogen peroxide under basic conditions. The addition of an organic base was found to be critical for achieving fast conversion reactions and the formation of the phenoxide anions. Addition of a nitrile group to the fluorenyl boronate ester moiety improved the stability of the material to photooxidation, increased the photoluminescence quantum yields, and enhanced the absorption and emission shifts to longer wavelengths. In real-time sensing measurements, films comprising the cyanofluorenyl boronate ester moiety and tetra- n-butylammonium hydroxide had a response time to acid-decomposed TATP vapor of seconds and a limit of detection of 40 ppb in 60 s.
The synthesis and properties of iridium cored dendrimers with carbazole dendrons
Publisher: Elsevier BV
Date: 04-2006
Nanostructured, Active Organic–Metal Junctions for Highly Efficient Charge Generation and Extraction in Polymer‐Fullerene Solar Cells
Publisher: Wiley
Date: 24-01-2012
Abstract: A facile one step method for periodic nanostructuring of organic solar cells is presented. The nanostructured metal-organic interface delivers combined enhanced light trapping and improved charge extraction leading to up to a 10% increase in power conversion efficiency of already optimized planar devices.
Influence of chromophore spacing on the stability and efficiency of host-free sky-blue dendrimer organic light emitting diodes
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TC00602B
Abstract: Doubly dendronized blue phosphorescent emitters promote more efficient and stable OLEDs than their singly dendronized counterparts. Degradation occurs as red electromer emission attributable to the detachment of the ligands and/or dendrons.
Solution‐Processible Phosphorescent Blue Dendrimers Based on Biphenyl‐Dendrons and Fac‐tris(phenyltriazolyl)iridium(III) Cores
Publisher: Wiley
Date: 06-10-2008
Carbazole/iridium dendrimer side-chain phosphorescent copolymers for efficient light emitting devices
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C1NJ20493A
Charge Transport without Recombination in Organic Solar Cells and Photodiodes
Publisher: American Chemical Society (ACS)
Date: 20-11-2015
A red emissive poly(dendrimer) for solution processed organic light-emitting diodes
Publisher: Elsevier BV
Date: 03-2020
Determining the absorption tolerance of single chromophore photodiodes for machine vision
Publisher: AIP Publishing
Date: 21-06-2010
DOI: 10.1063/1.3456374
Abstract: Color information is much less useful to machine vision systems than to people because the spectrum of light illuminating a scene is unknown. For scenes illuminated by daylight, color information can be made significantly more useful to machine vision systems if the scene is imaged using sensors with a specifically chosen combination of spectral responses. In this paper we show that detectors with a full width at half maximum of up to 100 nm can give good color discrimination, and that conjugated dendrimer chromophores have the spectral properties required to allow machine vision systems to confidently use color information.
Photophysical Properties of 9,10-Disubstituted Anthracene Derivatives in Solution and Films
Publisher: American Chemical Society (ACS)
Date: 08-06-2011
DOI: 10.1021/JP200668X
Abstract: We have carried out absorption, time-resolved fluorescence, and fluorescence quantum yield measurements of four new soluble anthracene derivatives. They show natural radiative lifetimes in the range of 2.5-4.4 ns, which is 5-10 times shorter than those reported for unsubstituted anthracene. The 9,10-bis(phenylethynyl)anthracene (BPEA) derivatives show the largest fluorescence transition dipoles, which is attributed to extended π-conjugation between anthracene and phenyls through acetylene linkages. Spin-cast films of the BPEA derivatives show strong fluorescence quenching by weakly emitting low energy excitations, which is attributed to excimer-like traps. Quenching is significantly reduced when bulky dendrons are attached so that they give maximum coverage of the emitting chromophore and prevent their aggregation. The results show that anthracene derivatives can be developed into efficient solution-processable fluorescent emitters for the blue and green spectral regions.
Hybrid Area‐Emitting Transistors: Solution Processable and with High Aperture Ratios
Publisher: Wiley
Date: 24-09-2015
Abstract: Area emission is realized in all-solution-processed hybrid light-emitting transistors (HLETs). A new HLET design is presented with increased aperture ratio, and optical and electrical characteristics are shown.
Advantage of suppressed non-Langevin recombination in low mobility organic solar cells
Publisher: AIP Publishing
Date: 07-07-2014
DOI: 10.1063/1.4887316
Abstract: Photovoltaic performance in relation to charge transport is studied in efficient (7.6%) organic solar cells (PTB7:PC71BM). Both electron and hole mobilities are experimentally measured in efficient solar cells using the resistance dependent photovoltage technique, while the inapplicability of classical techniques, such as space charge limited current and photogenerated charge extraction by linearly increasing voltage is discussed. Limits in the short-circuit current originate from optical losses, while charge transport is shown not to be a limiting process. Efficient charge extraction without recombination can be achieved with a mobility of charge carriers much lower than previously expected. The presence of dispersive transport with strongly distributed mobilities in high efficiency solar cells is demonstrated. Reduced non-Langevin recombination is shown to be beneficial for solar cells with imbalanced, low, and dispersive electron and hole mobilities.
Diffusion in Organic Film Stacks Containing Solution-Processed Phosphorescent Poly(dendrimer) Dopants
Publisher: American Chemical Society (ACS)
Date: 25-06-2021
PyThinFilm: Automated Molecular Dynamics Simulation Protocols for the Generation of Thin Film Morphologies
Publisher: American Chemical Society (ACS)
Date: 21-12-2023
The structural impact of water sorption on device-quality melanin thin films
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6SM02420C
Abstract: The melanins are a class of pigmentary bio-macromolecules ubiquitous in the biosphere. They possess an intriguing set of physico-chemical properties and have been shown to exhibit hybrid protonic-electronic electrical conductivity, a feature derived from a process termed chemical self-doping driven by the sorption of water. Although the mechanism underlying the electrical conduction has been established, how the sorbed water interacts with the melanin structure at the physical level has not. Herein we use neutron reflectometry to study changes in the structure of synthetic melanin thin films as a function of H
Tuning the Optoelectronic Properties of Nonfullerene Electron Acceptors
Publisher: Wiley
Date: 21-10-2014
Abstract: Broad spectral coverage over the solar spectrum is necessary for photovoltaic technologies and is a focus for organic solar cells. We report a series of small-molecule, nonfullerene electron acceptors containing the [(benzo[c][1,2,5]thiadiazol-4-yl)methylene]malononitrile unit as a high electron affinity component. The optoelectronic properties of these molecules were fine-tuned with the objective of attaining strong absorption at longer wavelengths by changing the low-ionization-potential moiety. The electron-accepting function of these materials was investigated with poly(3-n-hexylthiophene) (P3HT) as a standard electron donor. Significant photocurrent generation in the near infrared region, with an external quantum yield reaching as high as 22 % at 700 nm and an onset >800 nm was achieved. The results support efficient hole transfer to P3HT taking place after light absorption by the acceptor molecules. A Channel II-dominated power conversion efficiency of up to 1.5 % was, thus, achieved.
The development of phenylethylene dendrons for blue phosphorescent emitters
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B820235D
Solid State Dendrimer Sensors: Effect of Dendrimer Dimensionality on Detection and Sequestration of 2,4-Dinitrotoluene
Publisher: American Chemical Society (ACS)
Date: 30-08-2011
DOI: 10.1021/JP205586S
Determination of fullerene scattering length density: A critical parameter for understanding the fullerene distribution in bulk heterojunction organic photovoltaic devices
Publisher: American Chemical Society (ACS)
Date: 27-01-2014
DOI: 10.1021/LA403951J
Abstract: Fullerene derivatives are commonly used as electron acceptors in combination with (macro)molecular electron donors in bulk heterojunction (BHJ) organic photovoltaic (OPV) devices. Understanding the BHJ structure at different electron donor/acceptor ratios is critical to the continued improvement and development of OPVs. The high neutron scattering length densities (SLDs) of the fullerenes provide effective contrast for probing the distribution of the fullerene within the blend in a nondestructive way. However, recent neutron scattering studies on BHJ films have reported a wide range of SLDs ((3.6-4.4) × 10(-6) Å(-2)) for the fullerenes 60-PCBM and 70-PCBM, leading to differing interpretations of their distribution in thin films. In this article, we describe an approach for determining more precisely the scattering length densities of the fullerenes within a polymer matrix in order to accurately quantify their distribution within the active layers of OPV devices by neutron scattering techniques.
Time-Resolved Neutron Reflectometry and Photovoltaic Device Studies on Sequentially Deposited PCDTBT-Fullerene Layers
Publisher: American Chemical Society (ACS)
Date: 15-09-2014
DOI: 10.1021/LA5020779
Abstract: We have used steady-state and time-resolved neutron reflectometry to study the diffusion of fullerene derivatives into the narrow optical gap polymer poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) to explore the sequential processing of the donor and acceptor for the preparation of efficient organic solar cells. It was found that when [6,6]-phenyl-C61-butyric-acid-methyl-ester (60-PCBM) was deposited onto a thin film of PCDTBT from dichloromethane (DCM), a three-layer structure was formed that was stable below the glass-transition temperature of the polymer. When good solvents for the polymer were used in conjunction with DCM, both 60-PCBM and [6,6]-phenyl-C71-butyric-acid-methyl-ester (70-PCBM) were seen to form films that had a thick fullerene layer containing little polymer and a PCDTBT-rich layer near the interface with the substrate. Devices composed of films prepared by sequential deposition of the polymer and fullerene had efficiencies of up to 5.3%, with those based on 60-PCBM close to optimized bulk heterojunction (BHJ) cells processed in the conventional manner. Sequential deposition of pure components to form the active layer is attractive for large-area device fabrication, and the results demonstrate that this processing method can give efficient solar cells.
Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
Publisher: American Chemical Society (ACS)
Date: 04-08-2014
DOI: 10.1021/JA505330X
Abstract: The conventional picture of photocurrent generation in organic solar cells involves photoexcitation of the electron donor, followed by electron transfer to the acceptor via an interfacial charge-transfer state (Channel I). It has been shown that the mirror-image process of acceptor photoexcitation leading to hole transfer to the donor is also an efficient means to generate photocurrent (Channel II). The donor and acceptor components may have overlapping or distinct absorption characteristics. Hence, different excitation wavelengths may preferentially activate one channel or the other, or indeed both. As such, the internal quantum efficiency (IQE) of the solar cell may likewise depend on the excitation wavelength. We show that several model high-efficiency organic solar cell blends, notably PCDTBT:PC70BM and PCPDTBT:PC60/70BM, exhibit flat IQEs across the visible spectrum, suggesting that charge generation is occurring either via a dominant single channel or via both channels but with comparable efficiencies. In contrast, blends of the narrow optical gap copolymer DPP-DTT with PC70BM show two distinct spectrally flat regions in their IQEs, consistent with the two channels operating at different efficiencies. The observed energy dependence of the IQE can be successfully modeled as two parallel photodiodes, each with its own energetics and exciton dynamics but both having the same extraction efficiency. Hence, an excitation-energy dependence of the IQE in this case can be explained as the interplay between two photocurrent-generating channels, without recourse to hot excitons or other exotic processes.
Rivers of Light—Ternary Exciplex Blends for High Efficiency Solution‐Processed Red Phosphorescent Organic Light Emitting Diodes
Publisher: Wiley
Date: 11-11-2021
Abstract: Red‐emitting organic light‐emitting diodes (OLEDs) are important for displays and lighting, with the latter benefiting from solution processable materials, which would enable low embedded energy, scalable fabrication. Herein, the effect of annealing and phase separation on the performance of solution‐processed OLEDs incorporating a light‐emitting layer composed of the exciplex host, m‐MTDATA:OXD‐7, and a red phosphorescent light‐emitting dendrimer, Ir(tD C pq) 3 , is described. Solution‐processed OLEDs containing an annealed emissive layer with a low dendrimer concentration (2 wt%) are found to have the best performance, which is higher than the device in which the light‐emitting layer is not annealed. The improvement in the performance of the annealed device is ascribed to improved charge mobility within the emissive layer caused by phase separation of the OXD‐7. The OLEDs containing annealed m‐MTDATA:OXD‐7:(2 wt%) Ir(tD C pq) 3 have maximum current, power, and external quantum efficiencies of 17.9 cd A −1 , 19.4 lm W −1 , and 14.8 ± 0.6%, respectively. The fact that the maximum external quantum efficiency (EQE) of 14.8% is larger than that expected based on the photoluminescence quantum yield (PLQY) and the normal out‐coupling efficiency of 20% from a bottom‐emitting device is determined to arise from the different pathways of exciton formation under photoexcitation and charge injection.
A direct, heavy metal free synthesis of the β-1,6-linked GlcNAc disaccharide
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/CH11055
Abstract: The major component of the matrix of many bacterial biofilms is a linear polymer of β-1,6-linked units of N-acetylglucosamine (polysaccharide intercellular adhesin or poly-N-acetyl-β-1,6-d-glucosamine). In order to facilitate synthetic vaccine construction we have developed a direct, inexpensive, and biologically compatible synthesis of the minimal building block of this polymer, a β-1,6-linked GlcNAc disaccharide, namely 6-O-[2-acetamido-2-deoxy-β-d-glucopyranosyl]-2-acetamido-2-deoxy-d-glucopyranose.
Host-Free Blue Phosphorescent Dendrimer Organic Light-Emitting Field-Effect Transistors and Equivalent Light-Emitting Diodes: A Comparative Study
Publisher: American Chemical Society (ACS)
Date: 22-03-2017
Molecular weight dependent bimolecular recombination in organic solar cells
Publisher: AIP Publishing
Date: 04-08-2014
DOI: 10.1063/1.4891369
Abstract: Charge carrier recombination is studied in operational organic solar cells made from the polymer:fullerene system PCDTBT:PC71BM (poly[N-9′′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]: [6,6]-phenyl-C70-butyric acid methyl ester). A newly developed technique High Intensity Resistance dependent PhotoVoltage is presented for reliably quantifying the bimolecular recombination coefficient independently of variations in experimental conditions, thereby resolving key limitations of previous experimental approaches. Experiments are performed on solar cells of varying thicknesses and varying polymeric molecular weights. It is shown that solar cells made from low molecular weight PCDTBT exhibit Langevin recombination, whereas suppressed (non-Langevin) recombination is found in solar cells made with high molecular weight PCDTBT.
Elucidating the Spatial Arrangement of Emitter Molecules in Organic Light‐Emitting Diode Films
Publisher: Wiley
Date: 07-02-2017
Hole-transporting materials for low donor content organic solar cells: Charge transport and device performance
Publisher: Elsevier BV
Date: 2020
Simultaneous Enhancement of Brightness, Efficiency, and Switching in RGB Organic Light Emitting Transistors
Publisher: Wiley
Date: 20-08-2013
Abstract: An innovative design strategy for light emitting field effect transistors (LEFETs) to harvest higher luminance and switching is presented. The strategy uses a non-planar electrode geometry in tri-layer LEFETs for simultaneous enhancement of the key parameters of quantum efficiency, brightness, switching, and mobility across the RGB color gamut.
Electrochemical and spectroelectrochemical properties of building blocks for molecular arrays: Reactions of quinoxalino[2,3-b]porphyrins containing metal(II) ions
Publisher: World Scientific Pub Co Pte Lt
Date: 02-2005
DOI: 10.1142/S1088424605000216
Abstract: Quinoxalino[2,3-b]porphyrins are laterally-extended porphyrins with aromatic ring systems fused to the β,β'-positions of a pyrrolic ring of the macrocycle. They are building blocks for coplanar laterally-extended oligoporphyrins with applications in molecular electronics. The electrochemistry and spectroelectrochemistry of four such quinoxalinoporphyrins containing metal(II) ions and one free-base quinoxalinoporphyrin dissolved in nonaqueous media have been investigated and the data are compared to that seen for the same derivatives of the parent macrocycle lacking the fused quinoxaline ring. The investigated compounds are represented as (P)M and (PQ)M, where P = 5 ,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin, PQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b]porphyrin and M = 2 H , Zn , Cu , Ni or Pd . The complexes all undergo two ring-centered reductions and one or two ring-centered oxidations in PhCN , CH 2 Cl 2 , pyridine or THF . Additional redox reactions are also seen for the quinoxaline group in THF . The fusion of an electroactive quinoxaline group to the porphyrin macrocycle results in an 80 to 270 mV shift of E 1/2 towards easier reductions and the appearance of a third reduction which is assigned as a quinoxaline-centered redox process. The average HOMO-LUMO gap for the ( P ) M and ( PQ ) M derivatives is 2.26 ± 0.09 V and 2.14 ± 0.08 V , respectively. Both values are smaller than the average separation of 2.33 ± 0.13 V for the corresponding derivatives of tetraphenylporphyrin. The electrochemistry and UV-visible spectroelectrochemcal data indicate that moderate communication exists between the quinoxaline unit and the porphyrin π-ring system.
Simultaneous enhancement of charge generation quantum yield and carrier transport in organic solar cells
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TC02133B
Abstract: Bulk heterojunction (BHJ) organic solar cells and photodiodes require optimised active layer structures for both charge carrier photo-generation and extraction to occur efficiently.
Measuring the Magnetic Field Amplitude of rf Radiation by the Quasistatic Magnetic Field Effect in Organic Light-Emitting Diodes
Publisher: American Physical Society (APS)
Date: 06-2021
Fluoride Sensing by Catechol‐Based π‐Electron Systems
Publisher: Wiley
Date: 25-10-2010
Abstract: We have developed new catechol-based sensors that can detect fluoride via fluorescence or optical absorption even in the presence of other halides. The level and sensitivity of detection of the sensing molecules is dependent on the chromophore length, which is controlled by the number of thiophene units (one to three) within the chromophore. The sensor with three thiophene units, (E)-2-(2,2'-terthiophen-5-yl)-3-(3,4-dihydroxyphenyl)acrylonitrile, gives the best response to fluoride. By using fluorescence measurements fluoride is detectable over the concentration range 1.7 μM to 200 μM. Importantly, when adsorbed onto a solid support the fluorescent catechol dye can be used to detect the presence of fluoride in aqueous solution.
Facile Iterative Synthesis of Biphenyl Dendrons with a Functionalized Focus
Publisher: American Chemical Society (ACS)
Date: 08-09-2010
DOI: 10.1021/OL101717C
Abstract: An iterative procedure gives 1,3,5-phenyl-linked dendrons of up to the fourth generation and enables the formation of different generations of iridium(III) complex-cored dendrimers. The convergent synthesis uses N,N'-1,8-naphthyl-3,5-dibromophenylboronamide as the key building block. The iterative synthesis cycle involves deprotection of the boronamide-focused dendron to form a boronic acid and subsequent Suzuki coupling either with the N,N'-1,8-naphthyl-3,5-dibromophenylboronamide to give the next dendron generation or with an activated core to form a dendrimer.
Comparison of precursor polymer routes to and electronic properties of a new phenylacetylene derivatised poly[2-(2′-ethylhexyloxy)-1,4-phenylenevinylene]
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/A904274A
Effects of fluorination on iridium(III) complex phosphorescence: Magnetic circular dichroism and relativistic time-dependent density functional theory
Publisher: American Chemical Society (ACS)
Date: 16-02-2012
DOI: 10.1021/IC201899Z
Abstract: We use a combination of low temperature, high field magnetic circular dichroism, absorption, and emission spectroscopy with relativistic time-dependent density functional calculations to reveal a subtle interplay between the effects of chemical substitution and spin-orbit coupling (SOC) in a family of iridium(III) complexes. Fluorination at the ortho and para positions of the phenyl group of fac-tris(1-methyl-5-phenyl-3-n-propyl-[1,2,4]triazolyl)iridium(III) cause changes that are independent of whether the other position is fluorinated or protonated. This is demonstrated by a simple linear relationship found for a range of measured and calculated properties of these complexes. Further, we show that the phosphorescent radiative rate, k(r), is determined by the degree to which SOC is able to hybridize T(1) to S(3) and that k(r) is proportional to the inverse fourth power of the energy gap between these excitations. We show that fluorination in the para position leads to a much larger increase of the energy gap than fluorination at the ortho position. Theory is used to trace this back to the fact that fluorination at the para position increases the difference in electron density between the phenyl and triazolyl groups, which distorts the complex further from octahedral symmetry, and increases the energy separation between the highest occupied molecular orbital (HOMO) and the HOMO-1. This provides a new design criterion for phosphorescent iridium(III) complexes for organic optoelectronic applications. In contrast, the nonradiative rate is greatly enhanced by fluorination at the ortho position. This may be connected to a significant redistribution of spectral weight. We also show that the lowest energy excitation, 1A, has almost no oscillator strength therefore, the second lowest excitation, 2E, is the dominant emissive state at room temperature. Nevertheless the mirror image rule between absorption and emission is obeyed, as 2E is responsible for both absorption and emission at all but very low (<10 K) temperatures.
High-Triplet-Energy Dendrons: Enhancing the Luminescence of Deep Blue Phosphorescent Iridium(III) Complexes
Publisher: American Chemical Society (ACS)
Date: 10-07-2009
DOI: 10.1021/JA903157E
Abstract: Solution-processable blue phosphorescent emitters with high luminescence efficiency are highly desirable for large-area displays and lighting applications. This report shows that when a fac-tris[1-methyl-5-(4-fluorophenyl)-3-n-propyl-1H-[1,2,4]triazolyl]iridium(III) complex core is encapsulated by rigid high-triplet-energy dendrons, both the physical and photophysical properties can be optimized. The high-triplet-energy and rigid dendrons were composed of twisted biphenyl dendrons with the twisting arising from the use of tetrasubstituted branching phenyl rings. The blue phosphorescent dendrimer was synthesized using a convergent approach and was found to be solution-processable and to possess a high glass transition temperature of 148 degrees C. The dendrimer had an exceptionally high solution photoluminescence quantum yield (PLQY) of 94%, which was more than three times that of the simple parent core complex (27%). The rigid and high-triplet-energy dendrons were also found to control the intermolecular interactions that lead to the quenching of the luminescence in the solid state, and the film PLQY was found to be 60% with the emission having Commission Internationale de l'Eclairage coordinates of (0.16, 0.16). The results demonstrate that dendronization of simple chromophores can enhance their properties. Single layer neat dendrimer organic light-emitting diodes (OLEDs) had an external quantum efficiency (EQE) of 0.4% at 100 cd/m(2). Bilayer devices with an electron transport layer gave improved EQEs of up to 3.9%. Time-resolved luminescence measurements suggest that quenching of triplets by the electron transport layer used in the bilayer OLEDs limits performance.
Evolution and Morphology of Thin Films Formed by Solvent Evaporation: An Organic Semiconductor Case Study
Publisher: American Chemical Society (ACS)
Date: 26-08-2020
Enhancing the Properties of Ruthenium Dyes by Dendronization
Publisher: American Chemical Society (ACS)
Date: 29-05-2009
DOI: 10.1021/CM900838B
White Dendrimer Organic Light Emitting Diodes: Exciton Formation and Transfer
Publisher: Wiley
Date: 25-10-2020
Effect of Host Generation on the Luminescent and Charge Transporting Properties of Solution Processed OLEDs
Publisher: Wiley
Date: 29-09-2021
Abstract: Tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA) is a commonly used host material for organic light‐emitting diodes (OLEDs). TCTA has poor solubility and hence to improve solubility the authors have synthesized first‐ and second‐generation TCTA‐based dendrimers with n ‐propyl surface groups. These dendrimeric TCTA hosts have improved solubility and similar photophysical properties to TCTA. The hole mobility of solution‐processed TCTA is found to be an order of magnitude less than films formed by evaporation and similar to that of the two dendronized TCTAs (mobilities in the order of 10 −5 cm 2 V −1 s −1 ). The hole mobility in the films is found to decrease when a green emissive first‐generation light‐emitting dendrimer is blended with the host materials due to charge trapping on the emissive guest. In the case of the second‐generation host, there is evidence of a degree of phase separation in the film. Organic light‐emitting diodes are fabricated at guest concentrations corresponding to the maximum observed photoluminescence quantum yield (PLQY) and lowest hole mobility. It is found that the external quantum efficiency (EQE) does not always scale with the PLQY, leading to devices that have EQEs higher than expected based on the PLQY and outcoupling of light from a bottom emitting device.
Power losses in conventional and inverted non-polymeric donor:fullerene bulk heterojunction solar cells - The role of vertical phase separation in BQR:PC71BM blends
Publisher: Elsevier BV
Date: 09-2022
Two-Photon Absorption and Lasing in First-Generation Bisfluorene Dendrimers
Publisher: Wiley
Date: 19-05-2008
Morphology of OLED Film Stacks Containing Solution-Processed Phosphorescent Dendrimers
Publisher: American Chemical Society (ACS)
Date: 22-01-2018
Abstract: Organic light-emitting devices containing solution-processed emissive dendrimers can be highly efficient. The most efficient devices contain a blend of the light-emitting dendrimer in a host and one or more charge-transporting layers. Using neutron reflectometry measurements with in situ photoluminescence, we have investigated the structure of the as-formed film as well as the changes in film structure and dendrimer emission under thermal stress. It was found that the as-formed film stacks comprising poly(3,4-ethylenedioxythiophene):polystyrene sulfonate/host:dendrimer/1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (where the host was deuterated 4,4'-N,N'-di(carbazolyl)biphenyl or tris(4-carbazol-9-ylphenyl)amine, the host:dendrimer layer was solution-processed, and the 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene evaporated) had well-defined interfaces, indicating good wetting of each of the layers by the subsequently deposited layer. Upon thermal annealing, there was no change in the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate/host:dendrimer interface, but once the temperature reached above the T
Multi-layer organic light-emitting diodes processed from solution using phosphorescent dendrimers in a polymer host
Publisher: Elsevier BV
Date: 06-2010
Channel II photocurrent quantification in narrow optical gap polymer-fullerene solar cells with complimentary acceptor absorption
Publisher: AIP Publishing
Date: 03-06-2013
DOI: 10.1063/1.4808386
Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real-Time Sensing
Publisher: Wiley
Date: 26-10-2016
Effect of capping group on the properties of non-polymeric diketopyrrolopyrroles for solution-processed bulk heterojunction solar cells
Publisher: Elsevier BV
Date: 11-2017
A simple iterative method for the synthesis of β-(1→6)- glucosamine oligosaccharides
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.CARRES.2013.01.008
Abstract: Poly-N-acetylglucosamine (PNAG) saccharides are an important constituent of bacterial biofilms, such as those produced by Staphylococcus aureus. We have developed a simple two-step iterative method for the synthesis of β-(1→6)-glucosamine oligosaccharides that are structurally similar to PNAG. We illustrate the method with the formation of a pentasaccharide. The key building block is an orthogonally protected N-trifluoroacetamido thioglycoside donor that was added in succession to a glycosyl acceptor, enabling efficient glycosylation of the growing chain. In the second step of the iterative cycle, this building block is quantitatively deprotected at the C-6-hydroxyl position, ready for the next saccharide addition. Building from an azido-functionalised GlcNAc monosaccharide acceptor, the pentasaccharide was synthesised in seven steps in an overall yield of 25%.
Pentacene/K12 solar cells formed by organic vapor phase deposition
Publisher: SPIE-Intl Soc Optical Eng
Date: 08-08-2014
A three-dimensional multi-chromophore naphthalene diimide acceptor for polymer bulk heterojunction solar cells
Publisher: Elsevier BV
Date: 10-2020
Rigid, laterally-bridged bis-porphyrin system
Publisher: Royal Society of Chemistry (RSC)
Date: 1987
DOI: 10.1039/C39870000039
A Triarylamine-Based Anode Modifier for Efficient Organohalide Perovskite Solar Cells
Publisher: American Chemical Society (ACS)
Date: 03-03-2017
Abstract: Organohalide lead perovskite solar cells have emerged as a promising next-generation thin-film photovoltaic technology. It has been clearly recognized that interfacial engineering plays a critical role in cell performance. It has been also proposed that the open-circuit voltage is dependent on the ionization potential of the hole transport layer at the anode. In this communication, we report a simple modification of the anode with a triarylamine-based small molecule (1), which avoids the need to use standard hole transport materials and delivers a relatively high open-circuit voltage of 1.08 V and a power conversion efficiency of 16.5% in a simple planar architecture.
The Molecular Origin of Anisotropic Emission in an Organic Light-Emitting Diode
Publisher: American Chemical Society (ACS)
Date: 18-09-2017
DOI: 10.1021/ACS.NANOLETT.7B03528
Abstract: Atomistic nonequilibrium molecular dynamics simulations have been used to model the induction of molecular orientation anisotropy within the emission layer of an organic light-emitting diode (OLED) formed by vapor deposition. Two emitter species were compared: racemic fac-tris(2-phenylpyridine)iridium(III) (Ir(ppy)
Simple color tuning of phosphorescent dendrimer light emitting diodes
Publisher: AIP Publishing
Date: 11-04-2005
DOI: 10.1063/1.1899256
Abstract: A simple way of tuning the emission color in solution processed phosphorescent organic light emitting diodes is demonstrated. For each color a single emissive spin-coated layer consisting of a blend of three materials, a fac-tris(2-phenylpyridyl)iridium (III) cored dendrimer (Ir–G1) as the green emitter, a heteroleptic [bis(2-phenylpyridyl)-2-(2′-benzo[4,5-α]thienyl)pyridyl]iridium (III) cored dendrimer [Ir(ppy)2btp] as the red emitter, and 4,4′-bis(N-carbazolyl) biphenyl (CBP) as the host was employed. By adjusting the relative amount of green and red dendrimers in the blends, the color of the light emission was tuned from green to red. High efficiency two layer devices were achieved by evaporating a layer of electron transporting 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBI) on top of the spin-coated emissive layer. A brightness of 100cd∕m2 was achieved at drive voltages in the range 5.3–7.3 V. The peak external efficiencies at this brightness ranged from 31cd∕A(18lm∕W) to 7cd∕A(4lm∕W).
Loss Mechanisms in Fullerene-Based Low-Donor Content Organic Solar Cells
Publisher: American Chemical Society (ACS)
Date: 29-08-2018
Photo‐Rechargeable Battery Effect in First Generation Cationic‐Cyanine Dendrimers
Publisher: Wiley
Date: 30-07-2010
Triplet exciton diffusion in fac-tris(2-phenylpyridine) iridium(III)-cored electroluminescent dendrimers
Publisher: AIP Publishing
Date: 24-02-2005
DOI: 10.1063/1.1867571
Abstract: We have studied triplet-triplet annihilation in neat films of electrophosphorescent fac-tris(2-phenylpyridine) iridium(III) [Ir(ppy)3]-cored dendrimers containing phenylene- and carbazole-based dendrons with 2-ethylhexyloxy surface groups using time-resolved photoluminescence. From measured annihilation rates, the limiting current densities above which annihilation would dominate in dendrimer light-emitting devices are found to be & A∕cm2. The triplet exciton diffusion length varies in the range of 2–10 nm depending on the dendron size. The distance dependence of the nearest-neighbor hopping rate shows that energy transfer is dominated by the exchange mechanism.
Using charge collection narrowing to tune from broadband to narrowband all-polymer photodetectors
Publisher: IOP Publishing
Date: 25-10-2022
Abstract: We report an all-polymer photodiode comprising a new electron-transporting polymer, PNNTH , that contains naphthalene diimide and thiazole moieties. PNNTH has strong absorption at around 670 nm and an electron mobility of ≈10 −4 cm 2 V −1 s −1 . Bulk heterojunction films composed of PNNTH blended with the donor polymer, PBDTT-FTTE , in a weight ratio of 1:2 were found to have electron and hole mobilities of ≈10 −5 cm 2 V −1 s −1 and ≈10 −4 cm 2 V −1 s −1 , respectively. The photoresponse of conventional and inverted organic photodiodes containing the blend could be tuned from broadband (400–800 nm) to narrowband (50 nm full-width-at-half-maximum) simply by changing the thickness of the all-polymer blend. The narrowband response was achieved using the charge collection narrowing mechanism, which was enhanced by the unbalanced charge mobility. Transfer matrix-based optical modelling confirmed the wavelength dependence of the photoresponse. For both the broadband and narrowband photodiodes, the specific detectivity was greater than 10 11 Jones.
Unlocking the full potential of light emitting field-effect transistors by engineering charge injection layers
Publisher: Elsevier BV
Date: 11-2013
Spectral response tuning using an optical spacer in broad-band organic solar cells
Publisher: AIP Publishing
Date: 07-01-2013
DOI: 10.1063/1.4773556
Abstract: The effect of a zinc oxide optical spacer layer in broad-band polymer-fullerene solar cells is presented. The complimentary absorption in the donor and acceptor components allows photocurrent generation through photoinduced electron and hole-transfer mechanisms. Simulations of the optical-field distribution reveal that an optical spacer can be used to tune the spectral response to favor one photocurrent generation pathway via enhanced absorption in either the acceptor or donor component. Experimental results confirm these simulations, and the spacer is shown to enhance overall photocurrent in devices with thin active layers (& nm), with much less effect in thicker junctions (& nm).
Optimized multilayer indium-free electrodes for organic photovoltaics
Publisher: Wiley
Date: 09-10-2014
AZO/Ag/AZO anode for resonant cavity red, blue, and yellow organic light emitting diodes
Publisher: AIP Publishing
Date: 24-06-2016
DOI: 10.1063/1.4954689
Abstract: Indium tin oxide (ITO) is the transparent electrode of choice for organic light-emitting diodes (OLEDs). Replacing ITO for cost and performance reasons is a major drive across optoelectronics. In this work, we show that changing the transparent electrode on red, blue, and yellow OLEDs from ITO to a multilayer buffered aluminium zinc oxide/silver/aluminium zinc oxide (AZO/Ag/AZO) substantially enhances total output intensity, with better control of colour, its constancy, and intensity over the full exit hemisphere. The thin Ag containing layer induces a resonant cavity optical response of the complete device. This is tuned to the emission spectra of the emissive material while minimizing internally trapped light. A complete set of spectral intensity data is presented across the full exit hemisphere for each electrode type and each OLED colour. Emission zone modelling of output spectra at a wide range of exit angles to the normal was in excellent agreement with the experimental data and hence could, in principle, be used to check and adjust production settings. These multilayer transparent electrodes show significant potential for both eliminating indium from OLEDs and spectrally shaping the emission.
Diffusion - the Hidden Menace in Organic Optoelectronic Devices
Publisher: Wiley
Date: 29-12-2012
Emissive Material Optimization for Solution-Processed Exciplex OLEDs
Publisher: American Chemical Society (ACS)
Date: 08-11-2021
Solution-Processed Dendrimer-Based TADF Materials for Deep-Red OLEDs
Publisher: American Chemical Society (ACS)
Date: 30-11-2020
An external quantum efficiency of >20% from solution-processed poly(dendrimer) organic light-emitting diodes
Publisher: Springer Science and Business Media LLC
Date: 23-10-2018
DOI: 10.1038/S41528-018-0038-9
Abstract: Controlling the orientation of the emissive dipole has led to a renaissance of organic light-emitting diode (OLED) research, with external quantum efficiencies (EQEs) of % being reported for phosphorescent emitters. These highly efficient OLEDs are generally manufactured using evaporative methods and are comprised of small-molecule heteroleptic phosphorescent iridium(III) complexes blended with a host and additional layers to balance charge injection and transport. Large area OLEDs for lighting and display applications would benefit from low-cost solution processing, provided that high EQEs could be achieved. Here, we show that poly(dendrimer)s consisting of a non-conjugated polymer backbone with iridium(III) complexes forming the cores of first-generation dendrimer side chains can be co-deposited with a host by solution processing to give highly efficient devices. Simple bilayer devices comprising the emissive layer and an electron transport layer gave an EQE of % at luminances of up to ≈300 cd/m 2 , showing that polymer engineering can enable alignment of the emissive dipole of solution-processed phosphorescent materials.
ITO-free top emitting organic light emitting diodes with enhanced light out-coupling
Publisher: Wiley
Date: 06-11-2013
Determining the Correlation between Excited State Dynamics and Donor and Acceptor Structure in Nonfullerene Acceptors
Publisher: American Chemical Society (ACS)
Date: 11-08-2020
Fluorescent carbazole dendrimers for the detection of nitroaliphatic taggants and accelerants
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM32072J
Electrochemically tuneable multi-colour electrochemiluminescence using a single emitter
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6SC01912A
Abstract: A single component electrochemiluminescence system from which red, green, blue or white emission can be obtained, depending on the applied potential or the mode of the ECL experiment, is described.
Balanced carrier mobilities: Not a necessary condition for high-efficiency thin organic solar cells as determined by MIS-CELIV
Publisher: Wiley
Date: 09-10-2014
Sensitive and fast fluorescence-based indirect sensing of TATP
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9RA00693A
Abstract: We report fast and sensitive fluorescence “turn-on” sensing of TATP via hydrogen peroxide detection using fluorinated fluorenylboronate ester derivatives.
Thin film properties of triphenylamine-cored dendrimers: A molecular approach to control aggregation
Publisher: Elsevier BV
Date: 12-2013
Engineering dielectric constants in organic semiconductors
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7TC00893G
Abstract: An optical-frequency dielectric constant of 4.6 leads to improved charge generation efficiency in an organic semiconductor homojunction photovoltaic device.
The impact of film deposition and annealing on the nanostructure and dielectric constant of organic semiconductor thin films
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3CP03038E
Abstract: Different processing conditions lead to a range of molecular packing motifs for films of a novel organic semiconductor, which enables tuning of the optical frequency dielectric constant.
Light-emitting dendrimer:exciplex host-based solution-processed white organic light-emitting diodes
Publisher: Elsevier BV
Date: 2022
High-Sensitivity Poly(dendrimer)-Based Sensors for the Detection of Explosives and Taggant Vapors
Publisher: American Chemical Society (ACS)
Date: 17-02-2020
Structured-gate organic field-effect transistors
Publisher: IOP Publishing
Date: 18-05-2012
DOI: 10.1088/0022-3727/45/22/225105
Abstract: We report the fabrication and electrical characteristics of structured-gate organic field-effect transistors consisting of a gate electrode patterned with three-dimensional pillars. The pillar gate electrode was over-coated with a gate dielectric (SiO 2 ) and solution processed organic semiconductors producing both unipolar p-type and bipolar behaviour. We show that this new structured-gate architecture delivers higher source–drain currents, higher gate capacitance per unit equivalent linear channel area, and enhanced charge injection (electrons and/or holes) versus the conventional planar structure in all modes of operation. For the bipolar field-effect transistor (FET) the maximum source–drain current enhancements in p- and n-channel mode were % and 28%, respectively, leading to p and n charge mobilities with the same order of magnitude. Thus, we have demonstrated that it is possible to use the FET architecture to manipulate and match carrier mobilities of material combinations where one charge carrier is normally dominant. Mobility matching is advantageous for creating organic logic circuit elements such as inverters and lifiers. Hence, the method represents a facile and generic strategy for improving the performance of standard organic semiconductors as well as new materials and blends.
Erratum: “Bright electroluminescence from a conjugated dendrimer” [Appl. Phys. Lett. 81, 2285 (2002)]
Publisher: AIP Publishing
Date: 25-11-2002
DOI: 10.1063/1.1524029
Understanding the emission from dendrimers composed of thermally activated delayed fluorescence-based dendrons and a phosphorescent fac-tris[2-(thiophen-2-yl)-4-(phenyl)quinoline]iridium(i
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TC03979F
Abstract: Two light-emitting dendrimers composed of red phosphorescent fac -tris[2-(thiophen-2-yl)-4-(phenyl)quinoline]iridium( iii ) cores and either blue (BR) or green (GR) thermally activated delayed fluorescence-based (TADF-based) dendrons have been prepared.
Diffusion at Interfaces in OLEDs Containing a Doped Phosphorescent Emissive Layer
Publisher: Wiley
Date: 22-06-2016
Efficient organic photovoltaic cells on a single layer graphene transparent conductive electrode using MoOxas an interfacial layer
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6NR06942H
Abstract: The large surface roughness, low work function and high cost of transparent electrodes using multilayer graphene films can limit their application in organic photovoltaic (OPV) cells. Here, we develop single layer graphene (SLG) films as transparent anodes for OPV cells that contain light-absorbing layers comprised of the evaporable molecular organic semiconductor materials, zinc phthalocyanine (ZnPc)/fullerene (C60), as well as a molybdenum oxide (MoO
Narrow band green organic photodiodes for imaging
Publisher: Elsevier BV
Date: 11-2014
Spin–Orbit Coupling in Phosphorescent Iridium(III) Complexes
Publisher: Wiley
Date: 22-07-2011
Abstract: We study the excited states of two iridium(III) complexes with potential applications in organic light-emitting diodes: fac-tris(2-phenylpyridyl)iridium(III) [Ir(ppy)(3)] and fac-tris(1-methyl-5-phenyl-3-n-propyl-[1,2,4]triazolyl)iridium(III) [Ir(ptz)(3)]. Herein we report calculations of the excited states of these complexes from time-dependent density functional theory (TDDFT) with the zeroth-order regular approximation (ZORA). We show that results from the one-component formulation of ZORA, with spin-orbit coupling included perturbatively, accurately reproduce both the results of the two-component calculations and previously published experimental absorption spectra of the complexes. We are able to trace the effects of both scalar relativistic correction and spin-orbit coupling on the low-energy excitations and radiative lifetimes of these complexes. In particular, we show that there is an indirect relativistic stabilisation of the metal-to-ligand charge transfer (MLCT) states. This is important because it means that indirect relativistic effects increase the degree to which SOC can hybridise singlet and triplet states and hence plays an important role in determining the optical properties of these complexes. We find that these two compounds are remarkably similar in these respects, despite Ir(ppy)(3) and Ir(ptz)(3) emitting green and blue light respectively. However, we predict that these two complexes will show marked differences in their magnetic circular dichroism (MCD) spectra.
How reliable are efficiency measurements of perovskite solar cells? The first inter-comparison, between two accredited and eight non-accredited laboratories
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7TA05609E
Abstract: Towards improved reliability and relevance of indoor measurements of efficiency of perovskite solar cells.
Molecular versus exciton diffusion in fluorescence-based explosive vapour sensors
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC06367A
Abstract: Real time vapour detection efficiency is reliant on analyte diffusion rather than lified fluorescence quenching processes based on exciton diffusion.
High quality shadow masks for top contact organic field effect transistors using deep reactive ion etching
Publisher: IOP Publishing
Date: 28-06-2010
Charge Transport in a Highly Phosphorescent Iridium(III) Complex‐Cored Dendrimer with Double Dendrons
Publisher: Wiley
Date: 19-10-2011
Influence of molecular structure on the properties of dendrimer light-emitting diodes
Publisher: Elsevier BV
Date: 09-2003
A solution-processed bis-tridentate iridium(iii ) complex-cored dendrimer for green OLEDs
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TC01816G
Abstract: We report a solution-processable dendronised bis-tridentate iridium( iii ) complex composed of a bis(imidazolyl)phenyl ligand with a first-generation biphenyl dendron containing t -butyl surface groups and a 2-pyrazolyl-6-phenylpyridine co-ligand.
Pathway to high throughput, low cost indium-free transparent electrodes
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TA03248B
Abstract: A high throughput process is reported for the production of a highly conductive, transparent planar electrode comprising of silver nanowires and single walled carbon nanotubes imbedded into PEDOT:PSS.
Tunnelling conductance of vectorial porphyrin monolayers
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B802824A
Poly(dendrimers) with Phosphorescent Iridium(III) Complex-Based Side Chains Prepared via Ring-Opening Metathesis Polymerization
Publisher: American Chemical Society (ACS)
Date: 22-03-2012
DOI: 10.1021/MA300306D
Calculating transition dipole moments of phosphorescent emitters for efficient organic light-emitting diodes
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CP01045A
Abstract: Quantum-chemical calculations show that the direction of the transition dipole moment of organometallic phosphorescent emitters is sensitive to molecular geometry.
Slot-die coating of a formamidinium-cesium mixed-cation perovskite for roll-to-roll fabrication of perovskite solar cells under ambient laboratory conditions
Publisher: Elsevier BV
Date: 10-2022
Twisted Carbazole Dendrons for Solution-Processable Green Emissive Phosphorescent Dendrimers
Publisher: American Chemical Society (ACS)
Date: 03-2023
Amplified spontaneous emission and lasing properties of bisfluorene-cored dendrimers
Publisher: AIP Publishing
Date: 20-08-2007
DOI: 10.1063/1.2761833
Abstract: A study of the lified spontaneous emission (ASE) properties of three bisfluorene-cored dendrimers in the solid state is reported. The results show that the dendron type has a strong impact on the photoluminescence quantum yield and affects the ASE threshold, the optical gain, and loss coefficients. Optically pumped distributed feedback lasers operating in the blue spectral region were fabricated by spin coating the dendrimer films on top of a two-dimensional corrugated fused silica substrate. A best lasing threshold of 4.5μJ∕cm2 and a slope efficiency of 8.3% were obtained, which demonstrate the high potential of these materials for laser applications.
Synthesis and Properties of Highly Efficient Electroluminescent Green Phosphorescent Iridium Cored Dendrimers
Publisher: American Chemical Society (ACS)
Date: 12-2003
DOI: 10.1021/MA030383W
New Type II Catechol-Thiophene Sensitizers for Dye-Sensitized Solar Cells
Publisher: American Chemical Society (ACS)
Date: 16-09-2010
DOI: 10.1021/JP105687Z
Design protocols in triarylamine cored dendrimer-based explosive sensors
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2TC00541G
Dependence of Organic Interlayer Diffusion on Glass-Transition Temperature in OLEDs
Publisher: American Chemical Society (ACS)
Date: 13-04-2017
Abstract: Organic light-emitting diodes (OLEDs) are subject to thermal stress from Joule heating and the external environment. In this work, neutron reflectometry (NR) was used to probe the effect of heat on the morphology of thin three-layer organic films comprising materials typically found in OLEDs. It was found that layers within the films began to mix when heated to approximately 20 °C above the glass-transition temperature (T
Encapsulated Cores: Host-Free Organic Light-Emitting Diodes Based on Solution-Processible Electrophosphorescent Dendrimers
Publisher: Wiley
Date: 18-08-2005
Sensing nitroaromatic analytes with a bifluorene-cored dendrimer
Publisher: SPIE
Date: 20-08-2009
DOI: 10.1117/12.825821
Hole-Transporting Poly(dendrimer)s as Electron Donors for Low Donor Organic Solar Cells with Efficient Charge Transport
Publisher: American Chemical Society (ACS)
Date: 17-04-2020
All Solution‐Processed, Hybrid Light Emitting Field‐Effect Transistors
Publisher: Wiley
Date: 05-06-2014
Abstract: All solution-processed, high performance hybrid light emitting transistors (HLETs) are realized. Using a novel combination of device architecture and materials a bilayer device comprised of an inorganic and organic semiconducting layer is fabricated and the optoelectronic properties are presented.
Thermally activated delayed fluorescence poly(dendrimer)s – detrapping excitons for reverse intersystem crossing
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1TC05151B
Abstract: We compare the effect of donor strength on the optoelectronic properties of thermally activated delayed fluorescence poly(dendrimer)s and their dendrimer analogues.
Unambiguous detection of nitrated explosive vapours by fluorescence quenching of dendrimer films
Publisher: Springer Science and Business Media LLC
Date: 15-09-2015
DOI: 10.1038/NCOMMS9240
Abstract: Unambiguous and selective standoff (non-contact) infield detection of nitro-containing explosives and taggants is an important goal but difficult to achieve with standard analytical techniques. Oxidative fluorescence quenching is emerging as a high sensitivity method for detecting such materials but is prone to false positives—everyday items such as perfumes elicit similar responses. Here we report thin films of light-emitting dendrimers that detect vapours of explosives and taggants selectively—fluorescence quenching is not observed for a range of common interferents. Using a combination of neutron reflectometry, quartz crystal microbalance and photophysical measurements we show that the origin of the selectivity is primarily electronic and not the diffusion kinetics of the analyte or its distribution in the film. The results are a major advance in the development of sensing materials for the standoff detection of nitro-based explosive vapours, and deliver significant insights into the physical processes that govern the sensing efficacy.
Solution and solid-state electrochemiluminescence of a fac-tris(2-phenylpyridyl)iridium(III)-cored dendrimer
Publisher: Elsevier BV
Date: 06-2013
What are the threats from antimicrobial resistance for maternity units in low- and middle- income countries?
Publisher: Informa UK Limited
Date: 16-09-2016
DOI: 10.3402/GHA.V9.33381
The ‘double dendron’ approach to host free phosphorescent poly(dendrimer) OLEDs
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2PY00519K
Orange‐Red‐Light‐Emitting Field‐Effect Transistors Based on Phosphorescent Pt(II) Complexes with Area Emission
Publisher: Wiley
Date: 16-08-2016
Iridium Metal Complexes as an Unambiguous Probe of Intramolecular Vibrational Redistribution
Publisher: American Chemical Society (ACS)
Date: 14-08-2008
DOI: 10.1021/JA8036383
Abstract: Ultrafast luminescence spectroscopy has been undertaken on three iridium cored phosphorescent complexes, with the Ir(ppy)3 molecule being compared with two Ir(ppy)3 cored dendrimers. Energy dissipation by intramolecular vibrational redistribution (IVR) and cooling shows as a luminescence decay because it decreases the admixture of singlet character to the emitting triplet state. A larger amount of vibrational energy dissipates by IVR in dendrimer complexes. We have therefore found a methodology of obtaining unambiguous information on the IVR process and show its potential to study IVR rates as a function of vibrational energy.
Related Organisations
University Of Aberdeen School Of Medicine Medical Sciences And Nutrition
Location: United Kingdom of Great Britain and Northern Ireland
University Of Aberdeen
Location: United Kingdom of Great Britain and Northern Ireland
NHS Grampian
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
Advanced X-ray Facility For Structural Elucidation And Photocrystallography
Start Date: 2017
End Date: 2017
Funder: Australian Research Council
View Funded ActivityAn X-ray Diffraction Facility For Molecular Structure Determination
Start Date: 2007
End Date: 2007
Funder: Australian Research Council
View Funded ActivityA Nuclear Magnetic Resonance Facility For Modern Molecular Analysis
Start Date: 2016
End Date: 2016
Funder: Australian Research Council
View Funded ActivityElucidating The Morphology Of Organic Semiconductors At An Atomic Level
Start Date: 2020
End Date: 2021
Funder: Australian Research Council
View Funded Activity