ORCID Profile
0000-0002-4634-5376
Current Organisation
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Microelectronics and Integrated Circuits | Soft Condensed Matter | Molecular and Organic Electronics | Nanotechnology | Materials engineering | Optical Properties of Materials | Condensed Matter Physics | Macromolecular and Materials Chemistry | Synthesis of Materials | Mathematical Physics | Organic Chemical Synthesis | Photodetectors, Optical Sensors and Solar Cells | Electrical and Electronic Engineering | Nanofabrication growth and self assembly | Functional materials | Theoretical Physics | Electronic and Magnetic Properties of Condensed Matter; Superconductivity | Nonlinear Optics and Spectroscopy | Condensed Matter Physics—Electronic And Magnetic Properties;
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Integrated Circuits and Devices | Chemical sciences | Physical sciences | Expanding Knowledge in Technology | Defence not elsewhere classified | Expanding Knowledge in the Chemical Sciences |
Related Links
Publications
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
Synthesis of a porphyrin/conjugated polymer hybrid
Publisher: Elsevier BV
Date: 06-1999
High Performance p‐ and n‐Type Light‐Emitting Field‐Effect Transistors Employing Thermally Activated Delayed Fluorescence
Publisher: Wiley
Date: 21-05-2018
Low Threshold Room Temperature Polariton Lasing from Fluorene‐Based Oligomers
Publisher: Wiley
Date: 17-06-2021
Abstract: Organic semiconductors possessing tightly bound Frenkel excitons are known to be attractive candidates for demonstrating polariton lasing at room temperature. As polariton lasing can occur without inversion, it is a potential route to very low threshold coherent light sources. However, so far, the thresholds of organic polariton lasers have generally been much higher than those of organic photon lasers. Here this problem has been addressed by investigating two new organic molecules with a structure combining fluorene and carbazole groups. The materials are readily deposited from solution and exhibit high photoluminescence quantum yields, high absorption coefficients, and large radiative decay rates in neat films. Room temperature polariton lasing is realized in both materials with incident thresholds of 13.5 and 9.7 µJ cm −2 , corresponding to absorbed thresholds of 3.3 and 2.2 µJ cm −2 , respectively. These are the lowest values reported to date for polariton lasing in organic semiconductor materials, and approach typical values for organic photon lasers. The step‐like power dependent blue‐shift of polariton modes indicates an interplay between different depletion channels of the exciton reservoir. This work brings practical room temperature polaritonic devices and future realization of electrically driven polariton lasers a step closer.
The genome of the Wollemi pine, a critically endangered “living fossil” unchanged since the Cretaceous, reveals extensive ancient transposon activity
Publisher: Cold Spring Harbor Laboratory
Date: 24-08-2023
DOI: 10.1101/2023.08.24.554647
Abstract: We present the genome of the living fossil, Wollemia nobilis , a southern hemisphere conifer morphologically unchanged since the Cretaceous. Presumed extinct until rediscovery in 1994, the Wollemi pine is critically endangered with less than 60 wild adults threatened by intensifying bushfires in the Blue Mountains of Australia. The 12 Gb genome is among the most contiguous large plant genomes assembled, with extremely low heterozygosity and unusual abundance of DNA transposons. Reduced representation and genome re-sequencing of in iduals confirms a relictual population since the last major glacial/drying period in Australia, 120 ky BP. Small RNA and methylome sequencing reveal conservation of ancient silencing mechanisms despite the presence of thousands of active and abundant transposons, including some transferred horizontally to conifers from arthropods in the Jurassic. A retrotransposon burst 8-6 my BP coincided with population decline, possibly as an adaptation enhancing epigenetic ersity. Wollemia , like other conifers, is susceptible to Phytophthora , and a suite of defense genes, similar to those in loblolly pine, are targeted for silencing by sRNAs in leaves. The genome provides insight into the earliest seed plants, while enabling conservation efforts.
Liquid-phase sintering of lead halide perovskites and metal-organic framework glasses
Publisher: American Association for the Advancement of Science (AAAS)
Date: 29-10-2021
Abstract: Lead halide perovskites can exhibit bright, narrow band photoluminescence but have stability issues related to formation of inactive phases and the loss of lead ions. Hou et al . show that the black, photoactive phase of cesium lead iodide can be stabilized by forming a composite with a glassy phase of a metal-organic framework through liquid-phase sintering. The photoluminescence is at least two orders of magnitude greater than that of the pure perovskite. The glass stabilizes the perovskite under high laser excitation, and about 80% of the photoluminescence was maintained after 10,000 hours of water immersion. —PDS
The synthesis and properties of solution processable red-emitting phosphorescent dendrimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B400160E
Exciton–Exciton Annihilation in Thermally Activated Delayed Fluorescence Emitter
Publisher: Wiley
Date: 02-06-2020
High‐Performance, Solution‐Processed Non‐polymeric Organic Photodiodes
Publisher: Wiley
Date: 29-09-2014
Reduced Singlet–Triplet Annihilation for Low Threshold Amplified Spontaneous Emission from a Blue Polyfluorene Electroluminescent Organic Semiconductor
Publisher: American Chemical Society (ACS)
Date: 18-05-2022
Semitransparent and Low‐Voltage Operating Organic Light‐Emitting Field‐Effect Transistors Processed at Low Temperatures
Publisher: Wiley
Date: 04-04-2016
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.
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 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
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
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
Relativistic effects in a phosphorescent Ir(III) complex
Publisher: American Physical Society (APS)
Date: 21-01-2011
Application of Triplet–Triplet Annihilation Upconversion in Organic Optoelectronic Devices: Advances and Perspectives
Publisher: Wiley
Date: 10-2021
Abstract: Organic semiconductor materials have been widely used in various optoelectronic devices due to their rich optical and/or electrical properties, which are highly related to their excited states. Therefore, how to manage and utilize the excited states in organic semiconductors is essential for the realization of high‐performance optoelectronic devices. Triplet–triplet annihilation (TTA) upconversion is a unique process of converting two non‐emissive triplet excitons to one singlet exciton with higher energy. Efficient optical‐to‐electrical devices can be realized by harvesting sub‐bandgap photons through TTA‐based upconversion. In electrical‐to‐optical devices, triplets generated after the combination of electrons and holes also can be efficiently utilized via TTA, which resulted in a high internal conversion efficiency of 62.5%. Currently, many interesting explorations and significant advances have been demonstrated in these fields. In this review, a comprehensive summary of these intriguing advances on developing efficient TTA upconversion materials and their application in optoelectronic devices is systematically given along with some discussions. Finally, the key challenges and perspectives of TTA upconversion systems for further improvement for optoelectronic devices and other related research directions are provided. This review hopes to provide valuable guidelines for future related research and advancement in organic optoelectronics.
Solution-processed non-polymeric organic photodiodes
Publisher: SPIE
Date: 31-08-2015
DOI: 10.1117/12.2187583
Low Amplified Spontaneous Emission Threshold and Efficient Electroluminescence from a Carbazole Derivatized Excited-State Intramolecular Proton Transfer Dye
Publisher: American Chemical Society (ACS)
Date: 05-10-2018
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.
Preparation and crystallographic characterization of [MoCo(CO)5(PPh3)2(η5-C5H5)]
Publisher: Elsevier BV
Date: 06-1995
Green Phosphorescent Dendrimer for Light-Emitting Diodes
Publisher: Wiley
Date: 05-07-2002
DOI: 10.1002/1521-4095(20020705)14:13/14<975::AID-ADMA975>3.0.CO;2-D
Phenothiazine–Quinoline Conjugates Realizing Intrinsic Thermally Activated Delayed Fluorescence and Room-Temperature Phosphorescence: Understanding the Mechanism and Electroluminescence Devices
Publisher: Wiley
Date: 08-03-2021
High-performance solution-processed red hyperfluorescent OLEDs based on cibalackrot
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1TC04937B
Abstract: Solution-processed hyperfluorescent red organic light-emitting diodes with external quantum efficiencies of 15.3% was achieved by using cibalackrot as the fluorescent emitter, where attaching tert -butyl groups to the assistant host significantly contributes to device performance.
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.
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.
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.
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
Thermally Activated Delayed Fluorescence and Room-Temperature Phosphorescence in Asymmetric Phenoxazine-Quinoline (D2–A) Conjugates and Dual Electroluminescence
Publisher: American Chemical Society (ACS)
Date: 17-03-2022
Impact of Polymer Molecular Weight on Polymeric Photodiodes
Publisher: Wiley
Date: 29-11-2021
Abstract: The field of organic photodiodes (OPDs) has witnessed continuous development in the last decade. Although a considerable portion of electron‐donating materials are polymers, there has been an existential gap in deciphering the influence of the polymer's molecular‐weight on the photodiode performance. We take up OPDs based on 5,5′‐[(9,9‐Dioctyl‐9 H ‐fluorene‐2,7‐diyl)bis(2,1,3‐benzothiadiazole‐7,4diylmethylidyne)]bis[3‐ethyl‐2‐thioxo‐4‐thiazolidinone] (FBR) acceptor material blended with three different molecular‐weights of defect‐free form of a well‐known donor polymer poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) are taken up, and their optoelectronic performance along with morphological characteristics are studied. Disparity of up to a decade in key photodetecting characteristics is observed. Further, the tools of near‐edge X‐ray absorption fine‐structure spectroscopy, resonant soft X‐ray scattering spectroscopy, atomic force microscopy, and time‐delayed collection‐field measurements are employed to decipher the difference in the fundamental photo‐physical processes and the operating mechanisms of the OPDs. It is concluded that the molecular weight and the resulting morphology of the active layer strongly influence photodiode performance, in particular, dark current, linear dynamic range, and specific‐detectivity.
White Organic Light-Emitting Diodes from Single Emissive Layers: Combining Exciplex Emission with Electromer Emission
Publisher: American Chemical Society (ACS)
Date: 30-09-2021
Rotational Phenomena on Substituent Phenyl Rings of (η5‐Cyclopentadienyl)(η4‐Tetraphenylcyclobutadiene)Cobalt
Publisher: Wiley
Date: 10-1994
Multi-layer organic light-emitting diodes processed from solution using phosphorescent dendrimers in a polymer host
Publisher: Elsevier BV
Date: 06-2010
Effect of capping group on the properties of non-polymeric diketopyrrolopyrroles for solution-processed bulk heterojunction solar cells
Publisher: Elsevier BV
Date: 11-2017
Blue Phosphorescence from Iridium(III) Complexes at Room Temperature
Publisher: American Chemical Society (ACS)
Date: 26-09-2006
DOI: 10.1021/CM061173B
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
Design Strategy for Robust Organic Semiconductor Laser Dyes
Publisher: American Chemical Society (ACS)
Date: 09-01-2020
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
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.
Solution Processable Deep-Red Phosphorescent Pt(II) Complex: Direct Conversion from Its Pt(IV) Species via a Base-Promoted Reduction
Publisher: American Chemical Society (ACS)
Date: 21-06-2019
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).
Cibalackrot Dendrimers for Hyperfluorescent Organic Light‐Emitting Diodes
Publisher: Wiley
Date: 12-04-2022
Abstract: Hyperfluorescent organic light‐emitting diodes (HF‐OLEDs) enable a cascading Förster resonance energy transfer (FRET) from a suitable thermally activated delayed fluorescent (TADF) assistant host to a fluorescent end‐emitter to give efficient OLEDs with relatively narrowed electroluminescence compared to TADF‐OLEDs. Efficient HF‐OLEDs require optimal FRET with minimum triplet diffusion via Dexter‐type energy transfer (DET) from the TADF assistant host to the fluorescent end‐emitter. To hinder DET, steric protection of the end‐emitters has been proposed to disrupt triplet energy transfer. In this work, the first HF‐OLEDs based on structurally well‐defined macromolecules, dendrimers is reported. The dendrimers contain new highly twisted dendrons attached to a Cibalackrot core, resulting in high solubility in organic solvents. HF‐OLEDs based on dendrimer blend films are fabricated to show external quantum efficiencies of % at 100 cd m −2 . Importantly, dendronization with the bulky dendrons is found to have no negative impact to the FRET efficiency, indicating the excellent potential of the dendritic macromolecular motifs for HF‐OLEDs. To fully prevent the undesired triplet diffusion, Cibalackrot dendrimers HF‐OLEDs are expected to be further improved by adding additional dendrons to the Cibalackrot core and / or increasing dendrimer generations.
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
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.
The Development of Light-Emitting Dendrimers for Displays
Publisher: Wiley
Date: 02-07-2007
Low Light Amplification Threshold and Reduced Efficiency Roll‐Off in Thick Emissive Layer OLEDs from a Diketopyrrolopyrrole Derivative
Publisher: Wiley
Date: 11-04-2022
Abstract: External quantum efficiency (EQE) roll‐off under high current injection has been one of the major limiting factors toward the development of organic semiconductor laser diodes (OSLDs). While significant progress in this regard has been made on organic semiconductors (OSCs) emitting in the blue–green region of the visible spectrum, OSCs with longer wavelength emission ( nm) have fallen behind in both material development and the advancement in device architectures suitable for the realization of OSLDs. Therefore, to make simultaneous incremental advancements, a host–guest system comprising of a high performing poly(9,9‐dioctylfluorene‐ alt ‐benzothiadiazole) (F8BT) polymer and an efficient small molecule laser dye, dithiophenyl diketopyrrolopyrrole (DT‐DPP), is used. This combination provides an extremely low lified spontaneous emission threshold of 4.2 µJ cm −2 at an emission wavelength of 620 nm. The solution‐processed organic light‐emitting diodes (OLEDs) fabricated using this system exhibit a high external quantum efficiency (EQE) of 2.6% with low efficiency roll‐off and high current injection up to 90 A cm −2 to yield ultrahigh luminance of over 1.5 million cd m −2 .
Analysis of the emitting states of an Ir(III) complex with strong blue emission
Publisher: Elsevier BV
Date: 11-2015
Deep‐Red Lasing and Amplified Spontaneous Emission from Nature Inspired Bay‐Annulated Indigo Derivatives
Publisher: Wiley
Date: 14-11-2019
A rapid route to carbazole containing dendrons and phosphorescent dendrimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B717750J
Controlling triplet–triplet upconversion and singlet-triplet annihilation in organic light-emitting diodes for injection lasing
Publisher: Springer Science and Business Media LLC
Date: 29-04-2022
DOI: 10.1038/S43246-022-00248-0
Abstract: Significant progress has recently been made in the field of organic solid-state lasers. However, achieving lasing action from organic semiconductors under electrical excitation remains challenging due to losses introduced by triplet excitons. Here, we report experimental and theoretical results that confirm a positive contribution of triplet excitons for electrically-driven organic lasing via a bimolecular triplet-triplet upconversion (TTU) mechanism. We study a model fluorescent material, 9-(9-phenylcarbazole-3-yl)-10-(naphthalene-1-yl)anthracene, revealing that TTU can lower the threshold current densities required to achieve lasing under current injection. However, to achieve the best performance, the singlet-triplet annihilation (STA) must be simultaneously minimized. Hence, an experimental strategy to simultaneously obtain high TTU with low STA is demonstrated in host-guest system with coumarin 545T as the guest laser dye. This system has a low lified spontaneous emission threshold of 1.7 µJ cm − 2 under nanosecond optical pumping, and a more than three orders of magnitude improvement in J 50 in organic light-emitting diodes as compared to a reference blend.
Hybrid Light‐Emitting Transistors Based on Low‐Temperature Solution‐Processed Metal Oxides and a Charge‐Injecting Interlayer
Publisher: Wiley
Date: 19-11-2015
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.
Charge and exciton dynamics of OLEDs under high voltage nanosecond pulse: towards injection lasing
Publisher: Springer Science and Business Media LLC
Date: 27-08-2020
DOI: 10.1038/S41467-020-18094-4
Abstract: Electrical pumping of organic semiconductor devices involves charge injection, transport, device on/off dynamics, exciton formation and annihilation processes. A comprehensive model analysing those entwined processes together is most helpful in determining the dominating loss pathways. In this paper, we report experimental and theoretical results of Super Yellow (Poly( p -phenylene vinylene) co-polymer) organic light emitting diodes operating at high current density under high voltage nanosecond pulses. We demonstrate complete exciton and charge carrier dynamics of devices, starting from charge injection to light emission, in a time scale spanning from the sub-ns to microsecond region, and compare results with optical pumping. The experimental data is accurately replicated by simulation, which provides a robust test platform for any organic materials. The universality of our model is successfully demonstrated by its application to three other laser active materials. The findings provide a tool to narrow the search for material and device designs for injection lasing.
Nano-Alignment in Semiconducting Polymer Films: A Path to Achieve High Current Density and Brightness in Organic Light Emitting Transistors
Publisher: American Chemical Society (ACS)
Date: 27-02-2018
Solid cyclooctatetraene-based triplet quencher demonstrating excellent suppression of singlet–triplet annihilation in optical and electrical excitation
Publisher: Springer Science and Business Media LLC
Date: 06-11-2020
DOI: 10.1038/S41467-020-19443-Z
Abstract: Triplet excitons have been identified as the major obstacle to the realisation of organic laser diodes, as accumulation of triplet excitons leads to significant losses under continuous wave (CW) operation and/or electrical excitation. Here, we report the design and synthesis of a solid-state organic triplet quencher, as well as in-depth studies of its dispersion into a solution processable bis-stilbene-based laser dye. By blending the laser dye with 20 wt% of the quencher, negligible effects on the ASE thresholds, but a complete suppression of singlet–triplet annihilation (STA) and a 20-fold increase in excited-state photostability of the laser dye under CW excitation, were achieved. We used small-area OLEDs (0.2 mm 2 ) to demonstrate efficient STA suppression by the quencher in the nanosecond range, supported by simulations to provide insights into the observed STA quenching under electrical excitation. The results demonstrate excellent triplet quenching ability under both optical and electrical excitations in the nanosecond range, coupled with excellent solution processability.
Low Amplified Spontaneous Emission and Lasing Thresholds from Hybrids of Fluorenes and Vinylphenylcarbazole
Publisher: Wiley
Date: 26-08-2020
Lasing Operation under Long‐Pulse Excitation in Solution‐Processed Organic Gain Medium: Toward CW Lasing in Organic Semiconductors
Publisher: Wiley
Date: 09-09-2020
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
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
Probing polaron-induced exciton quenching in TADF based organic light-emitting diodes
Publisher: Springer Science and Business Media LLC
Date: 11-01-2022
DOI: 10.1038/S41467-021-27739-X
Abstract: Polaron-induced exciton quenching in thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes (OLEDs) can lead to external quantum efficiency (EQE) roll-off and device degradation. In this study, singlet-polaron annihilation (SPA) and triplet-polaron annihilation (TPA) were investigated under steady-state conditions and their relative contributions to EQE roll-off were quantified, using experimentally obtained parameters. It is observed that both TPA and SPA can lead to efficiency roll-off in 2,4,5,6-tetra(9 H -carbazol-9-yl)isophthalonitrile (4CzIPN) doped OLEDs. Charge imbalance and singlet-triplet annihilation (STA) were found to be the main contributing factors, whereas the device degradation process is mainly dominated by TPA. It is also shown that the impact of electric field-induced exciton dissociation is negligible under the DC operation regime (electric field 0.5 MV cm −1 ). Through theoretical simulation, it is demonstrated that improvement to the charge recombination rate may reduce the effect of polaron-induced quenching, and thus significantly decrease the EQE roll-off.
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
Mobility Evaluation of [1]Benzothieno[3,2-b][1]benzothiophene Derivatives: Limitation and Impact on Charge Transport
Publisher: American Chemical Society (ACS)
Date: 24-12-2018
Abstract: Among contemporary semiconductors, many of the best performing materials are based on [1]benzothieno[3,2- b][1]benzothiophene (BTBT). Alkylated derivatives of these small molecules not only provide high hole mobilities but also can be easily processed by thermal vacuum or solution deposition methods. Over the last decade, numerous publications have investigated molecular structures and charge transport properties to elucidate what makes these molecules so special. However, the race toward ever higher mobilities resulted in significantly deviating values, which exacerbates linking molecular structure to electronic properties. Moreover, a recently arisen debate on overestimation of organic field-effect transistor mobilities calls for a revaluation of these numbers. We synthesized and characterized four BTBT derivatives with either one or two alkyl chains (themselves consisting of either 8 or 10 carbon atoms) and investigated their spectroscopic, structural, and electrical properties. By employing two-probe, gated four-point probe and gated van der Pauw measurements, we compare field-effect mobility values at room and low temperatures and discuss their feasibility and viability. We attribute mobility changes to different angles between molecule planes and core-to-core double-layer stacking of asymmetric BTBT derivatives and show higher mobilities in the presence of more and longer alkyl chains. A so-called "zipper effect" brings BTBT cores in closer proximity promoting stronger intermolecular orbital coupling and hence higher charge transport.
67.1: Invited Paper: Dendrimers — Efficient Solution-Processed Phosphorescent OLED Materials
Publisher: Wiley
Date: 2005
DOI: 10.1889/1.2036382
Conjugated dendrimers: a modular approach to materials for full-color displays
Publisher: SPIE
Date: 16-02-2004
DOI: 10.1117/12.512062
Narrow band green organic photodiodes for imaging
Publisher: Elsevier BV
Date: 11-2014
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
Reactions of molybdenum-cobalt complex with phenylacetylene: X-ray crystal structure of [MoCo(CO)4{CPhCHCHCPh}(η5-C5H5)]
Publisher: Elsevier BV
Date: 06-1995
Fluorenone and triphenylamine based donor–acceptor–donor (D–A–D) for solution-processed organic light-emitting diodes
Publisher: IOP Publishing
Date: 20-05-2022
Abstract: In this work, we describe the design and synthesis of a novel, organic emissive small donor–acceptor–donor molecule, 3,6-bis(4-(bis(4-methoxyphenyl)amino)phenyl)-9 H -fluoren-9-one, and its incorporation into functional organic light-emitting diode (OLED) devices. The molecule was developed through a three-step procedure with high yields using low-cost and commercially available materials. Photophysical analysis shows emission from both locally excited (LE) and intramolecular charge transfer (ICT) fluorescent states, leading to broad emission spectra with a high solution photoluminescence quantum yield of 73%. Time resolved and temperature dependent photoluminescence measurements were utilized to obtain insights about emission mechanism from LE and ICT states. The presence of broad emission was further confirmed using density functional theory calculations. After optimal design and selection of the film thickness and host matrix, an OLED using a solution-processed host: dopant emissive layer with 10 wt% dopant exhibited a maximum current efficiency, power efficiency and external quantum efficiency of 2.6 cd A −1 , 2.5 lm W −1 and 1.5%, respectively.
High EQE and High Brightness Solution‐Processed TADF Light‐Emitting Transistors and OLEDs
Publisher: Wiley
Date: 06-07-2020
Aggregates of diketopyrrolopyrrole dimers in solution
Publisher: Elsevier BV
Date: 2017
Influence of molecular structure on the properties of dendrimer light-emitting diodes
Publisher: Elsevier BV
Date: 09-2003
Charge Transport in a Highly Phosphorescent Iridium(III) Complex‐Cored Dendrimer with Double Dendrons
Publisher: Wiley
Date: 19-10-2011
Reactions of Na[Mo(CO)3(η5-C5H5)] towards CoCl(PPh3)3 and CoCl(P(OMe)3)5: X-ray crystal structures of [MoCo(CO)6(PPh3)(η5-C5H5)] and [Mo(CO)3(P(OMe)3)(η5-C5H5)]2
Publisher: Elsevier BV
Date: 08-1996
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
Correlating Exciton Dynamics of Thermally Activated Delayed-Fluorescence Emitters to Efficiency Roll-Off in OLEDs
Publisher: American Physical Society (APS)
Date: 28-11-2022
Synthesis and Properties of Highly Efficient Electroluminescent Green Phosphorescent Iridium Cored Dendrimers
Publisher: American Chemical Society (ACS)
Date: 12-2003
DOI: 10.1021/MA030383W
Amplified Spontaneous Emission from Zwitterionic Excited-State Intramolecular Proton Transfer
Publisher: American Chemical Society (ACS)
Date: 21-07-2022
DOI: 10.1021/JACS.2C02163
Abstract: The unique four-level photocycle characteristics of excited-state intramolecular proton transfer (ESIPT) materials enable population inversion and large spectral separation between absorption and emission through their respective enol and keto forms. This leads to minimal or no self-absorption losses, a favorable feature in acting as an optical gain medium. While conventional ESIPT materials with an enol-keto tautomerism process are widely known, zwitterionic ESIPT materials, particularly those with high photoluminescence, are scarce. Facilitated by the synthesis and characterization of a new family of 2-hydroxyphenyl benzothiazole (HBT) with fluorene substituents,
Comparative fiscal illusion: a fiscal illusion index for the European Union
Publisher: Springer Science and Business Media LLC
Date: 12-05-2013
Encapsulated Cores: Host-Free Organic Light-Emitting Diodes Based on Solution-Processible Electrophosphorescent Dendrimers
Publisher: Wiley
Date: 18-08-2005
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
UV–Deep Blue–Visible Light‐Emitting Organic Field Effect Transistors with High Charge Carrier Mobilities
Publisher: Wiley
Date: 15-03-2017
Sensing nitroaromatic analytes with a bifluorene-cored dendrimer
Publisher: SPIE
Date: 20-08-2009
DOI: 10.1117/12.825821
High‐Speed OLEDs and Area‐Emitting Light‐Emitting Transistors from a Tetracyclic Lactim Semiconducting Polymer
Publisher: Wiley
Date: 15-08-2018
Triplet-Triplet Upconversion in Organic Light- Emitting Diodes: Implications to Injection Lasing
Publisher: Research Square Platform LLC
Date: 15-09-2020
DOI: 10.21203/RS.3.RS-74957/V1
Abstract: While significant progress has been made over last few years in the field of organic solid-state lasers, achieving lasing action from organic semiconductors under electrical excitation still remains a big challenge. One of the major barriers towards electrically pumped organic lasers are optical losses due to triplet excitons. In this work, we report both experimental and theoretical results that confirm positive contribution of triplet excitons for the scope of electrically driven organic laser. We studied a model fluorescence material, 9-(9-phenylcarbazole-3-yl)-10(naphthalene-1-yl) anthracene and reveals that the threshold current densities required to achieve lasing emission under electrical injection can be significantly reduced with the aid of triplet-triplet exciton upconversion processes. Furthermore, we demonstrate that, to achieve the best performance, the singlet-triplet exciton annihilation must be minimized. These results are unprecedented and provide a pathway towards development of new class of triplet-triplet upconversion materials for injection laser.
Non-radiative decay mechanisms in blue phosphorescent iridium(III) complexes
Publisher: Elsevier BV
Date: 06-2008
Structural Integration of Carbazole and Tetraphenylethylene: Ultrafast Excited‐State Relaxation Dynamics and Efficient Electroluminescence
Publisher: Wiley
Date: 25-02-2021
Organic Light‐Emitting Transistors: Advances and Perspectives
Publisher: Wiley
Date: 04-11-2019
Solution and solid-state electrochemiluminescence of a fac-tris(2-phenylpyridyl)iridium(III)-cored dendrimer
Publisher: Elsevier BV
Date: 06-2013
High‐Performance, Fullerene‐Free Organic Photodiodes Based on a Solution‐Processable Indigo
Publisher: Wiley
Date: 22-09-2015
Abstract: A solution-processable dibromoindigo with an alkyoxyphenyl solubilizing group is developed and used as a new electron acceptor in organic photodiodes. The solution-processed fullerene-free organic photodiodes show an almost spectrally flat response with a high responsivity (0.4 A W(-1)) and a high detectivity (1 × 10(12) Jones). These values are comparable to silicon-based photodiodes.
Orange‐Red‐Light‐Emitting Field‐Effect Transistors Based on Phosphorescent Pt(II) Complexes with Area Emission
Publisher: Wiley
Date: 16-08-2016
The ‘double dendron’ approach to host free phosphorescent poly(dendrimer) OLEDs
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2PY00519K
Strong coupling and energy funnelling in an electrically conductive organic blend
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TC02239J
Abstract: A host–guest matrix enables both strong exciton-photon coupling and efficient energy transfer. This combination holds promise toward reduced laser thresholds and eventual electrical injection.
The synthesis and properties of iridium cored dendrimers with carbazole dendrons
Publisher: Elsevier BV
Date: 04-2006
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 Oxford
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
Discovery Projects - Grant ID: DP120103726
Start Date: 2012
End Date: 01-2016
Amount: $400,000.00
Funder: Australian Research Council
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End Date: 03-2012
Amount: $150,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP200103036
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End Date: 03-2024
Amount: $390,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP140101088
Start Date: 2014
End Date: 12-2017
Amount: $230,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP160100700
Start Date: 2016
End Date: 12-2020
Amount: $520,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP1093224
Start Date: 2010
End Date: 12-2013
Amount: $363,500.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE230100070
Start Date: 10-2023
End Date: 10-2024
Amount: $740,700.00
Funder: Australian Research Council
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