ORCID Profile
0000-0002-9049-7414
Current Organisation
NSW Ministry of Health
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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)
Nanotechnology | Optics And Opto-Electronic Physics | Condensed Matter Physics—Electronic And Magnetic Properties; | Molecular and Organic Electronics | Nanotechnology | Biophysics | Materials Engineering | Soft Condensed Matter | Polymers | Condensed Matter Physics | Photodetectors, Optical Sensors and Solar Cells | Macromolecular and Materials Chemistry | Biotechnology Not Elsewhere Classified | Interdisciplinary Engineering Not Elsewhere Classified | Materials Engineering Not Elsewhere Classified | Biochemistry And Cell Biology Not Elsewhere Classified | Quantum Physics | Physical Chemistry of Materials | Synthesis Of Macromolecules | Chemical Spectroscopy | Optical Physics | Colloid And Surface Chemistry | Chemical Sciences Not Elsewhere Classified | Physical Chemistry Of Macromolecules | Biological Physics | Biological Sciences Not Elsewhere Classified | Functional Materials | Other Electronic Engineering | Compound Semiconductors | Organic Chemistry Not Elsewhere Classified | Applied Economics | Biosensor Technologies | Metals and Alloy Materials | Organic Semiconductors | Ceramics | Photonics, Optoelectronics and Optical Communications | Condensed Matter Physics—Structural Properties | Condensed Matter Physics—Other | Quantum Optics And Lasers | Engineering Systems Design | Organic Chemistry | Bioinorganic Chemistry | Biomaterials | Inorganic Chemistry | Biomedical Engineering | Biomaterials | Electrical and Electronic Engineering | Agricultural Biotechnology not elsewhere classified | Theory Of Materials | Nanoscale Characterisation | Agricultural Economics | Nanomaterials | Other Physical Sciences | Macromolecular and Materials Chemistry not elsewhere classified | Process Control And Simulation | Atomic And Molecular Physics | Nanoelectronics
ANZSRC Socio-Economic Objective (SEO)
Physical sciences | Integrated circuits and devices | Chemical sciences | Expanding Knowledge in Technology | Solar-photoelectric | Integrated Circuits and Devices | Skin and related disorders | Biological sciences | Diagnostic methods | Expanding Knowledge in the Physical Sciences | Communication equipment not elsewhere classified | Plant Production and Plant Primary Products not elsewhere classified | Economic Growth | Computer Hardware and Electronic Equipment not elsewhere classified | Emerging Defence Technologies | National Security | Other | Structural Metal Products | Organic industrial chemicals not classified elsewhere | Environmentally Sustainable Plant Production not elsewhere classified | Plastic products (incl. Construction materials) | Other | Energy storage | Cancer and related disorders | Scientific instrumentation | Energy not elsewhere classified | Polymeric materials (e.g. paints) | Defence not elsewhere classified | Diagnostic Methods | Expanding Knowledge in Engineering |
Related Links
Publications
Large area monolithic organic solar cells
Publisher: SPIE
Date: 27-11-2012
DOI: 10.1117/12.999270
Partial genetic deletion of neuregulin 1 and adolescent stress interact to alter NMDA receptor binding in the medial prefrontal cortex
Publisher: Frontiers Media SA
Date: 29-09-2014
Genetic deletion of P-glycoprotein alters stress responsivity and increases depression-like behavior, social withdrawal and microglial activation in the hippocampus of female mice
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.BBI.2017.05.008
Abstract: P-glycoprotein (P-gp) is an ABC transporter expressed at the blood brain barrier and regulates the brain uptake of various xenobiotics and endogenous mediators including glucocorticoid hormones which are critically important to the stress response. Moreover, P-gp is expressed on microglia, the brain's immune cells, which are activated by stressors and have an emerging role in psychiatric disorders. We therefore hypothesised that germline P-gp deletion in mice might alter the behavioral and microglial response to stressors. Female P-gp knockout mice displayed an unusual, frantic anxiety response to intraperitoneal injection stress in the light-dark test. They also tended to display reduced conditioned fear responses compared to wild-type (WT) mice in a paradigm where a single electric foot-shock stressor was paired to a context. Foot-shock stress reduced social interaction and decreased microglia cell density in the amygdala which was not varied by P-gp genotype. Independently of stressor exposure, female P-gp deficient mice displayed increased depression-like behavior, idiosyncratic darting behavior, age-related social withdrawal and hyperactivity, facilitated sensorimotor gating and altered startle reactivity. In addition, P-gp deletion increased microglia cell density in the CA3 region of the hippoc us, and the microglial cells exhibited a reactive, hypo-ramified morphology. Further, female P-gp KO mice displayed increased glucocorticoid receptor (GR) expression in the hippoc us. In conclusion, this research shows that germline P-gp deletion affected various behaviors of relevance to psychiatric conditions, and that altered microglial cell activity and enhanced GR expression in the hippoc us may play a role in mediating these behaviors.
Convergent Proton-Transfer Photocycles Violate Mirror-Image Symmetry in a Key Melanin Monomer
Publisher: American Chemical Society (ACS)
Date: 05-2007
DOI: 10.1021/JA069280U
Reduced Recombination in High Efficiency Molecular Nematic Liquid Crystalline: Fullerene Solar Cells
Publisher: Wiley
Date: 23-08-2016
Charge Transport without Recombination in Organic Solar Cells and Photodiodes
Publisher: American Chemical Society (ACS)
Date: 20-11-2015
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.
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
The Effect of Direct Electron Beam Patterning on the Water Uptake and Ionic Conductivity of Nafion Thin Films
Publisher: Wiley
Date: 15-06-2023
Abstract: The effect of electron‐beam patterning on the water uptake and ionic conductivity of Nafion films using a combination of X‐ray photoelectron spectroscopy, quartz crystal microbalance studies, neutron reflectometry, and impedance spectroscopy is reported. The aim is to further characterize the nanoscale patterned Nafion structures recently used as a key element in novel ion‐to‐electron transducers by Gluschke et al. To enable this, the electron beam patterning process is developed for large areas, achieving patterning speeds approaching 1 cm 2 h −1 , and patterned areas as large as 7 cm 2 for the neutron reflectometry studies. It is ultimately shown that electron‐beam patterning affects both the water uptake and the ionic conductivity, depending on film thickness. Type‐II adsorption isotherm behavior is seen for all films. For thick films (≈230 nm), a strong reduction in water uptake with electron‐beam patterning is found. In contrast, for thin films (≈30 nm), electron‐beam patterning enhances water uptake. Notably, for either thickness, the reduction in ionic conductivity arising from electron‐beam patterning is kept to less than an order of magnitude. Mechanisms are proposed for the observed behavior based on the known complex morphology of Nafion films to motivate future studies of electron‐beam processed Nafion.
Electrochemical synthesis of melanin free-standing films
Publisher: Elsevier BV
Date: 11-2005
Ligand-assisted cation-exchange engineering for high-efficiency colloidal Cs1−xFAxPbI3 quantum dot solar cells with reduced phase segregation
Publisher: Springer Science and Business Media LLC
Date: 20-01-2020
Study of optical properties of electropolymerized melanin films by photopyroelectric spectroscopy
Publisher: Springer Science and Business Media LLC
Date: 12-11-2006
DOI: 10.1007/S00249-005-0020-Z
Abstract: Photopyroelectric (PPE) spectroscopy, in the 350-1,075 nm wavelength range, was used to study the optical properties of electropolymerized melanin films on indium tin oxide (ITO) coated glass. The PPE intensity signal as a function of the wavelength lambda, V (n)(lambda) and its phase F (n)(lambda) were independently measured. Using the PPE signal intensity and the thermal and optical properties of the pyroelectric detector, we were able to calculate the optical absorption coefficient beta of melanin in the solid-state. We believe this to be the first such measurement of its kind on this material. Additionally, we found an optical gap in these melanin films at 1.70 eV.
Decoupling Ionic and Electronic Currents in Melanin
Publisher: Wiley
Date: 10-2018
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
Nrg1 deficiency modulates the behavioural effects of prenatal stress in mice
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.PNPBP.2018.06.013
Abstract: Little is known about the exact genes that confer vulnerability or resilience to environmental stressors during early neurodevelopment. Partial genetic deletion of neuregulin 1 (Nrg1) moderates the neurobehavioural effects of stressors applied in adolescence and adulthood, however, no study has yet examined its impact on prenatal stress. Here we examined whether Nrg1 deficiency in mice modulated the impact of prenatal stress on various behaviours in adulthood. Male heterozygous Nrg1 mice were mated with wild-type female mice who then underwent daily restraint stress from days 13 to 19 of gestation. Surprisingly, prenatal stress had overall beneficial effects by facilitating sensorimotor gating, increasing sociability, decreasing depressive-like behaviour, and improving spatial memory in adulthood. Such benefits were not due to any increase in maternal care, as prenatal stress decreased nurturing of the offspring. Nrg1 deficiency negated the beneficial behavioural effects of prenatal stress on all measures except sociability. However, Nrg1 deficiency interacted with prenatal stress to trigger locomotor hyperactivity. Nrg1 deficiency, prenatal stress or their combination failed to alter acute stress-induced plasma corticosterone concentrations. Collectively these results demonstrate that Nrg1 deficiency moderates the effects of prenatal stress on adult behaviour, but it does so in a complex, domain-specific fashion.
On the origin of electrical conductivity in the bio-electronic material melanin
Publisher: AIP Publishing
Date: 27-02-2012
DOI: 10.1063/1.3688491
Abstract: The skin pigment melanin is one of a few bio-macromolecules that display electrical and photo-conductivity in the solid-state. A model for melanin charge transport based on amorphous semiconductivity has been widely accepted for 40 years. In this letter, we show that a central pillar in support of this hypothesis, namely experimental agreement with a hydrated dielectric model, is an artefact related to measurement geometry and non-equilibrium behaviour. Our results cast significant doubt on the validity of the amorphous semiconductor model and are a reminder of the difficulties of electrical measurements on low conductivity, disordered organic materials.
High‐Performance, Solution‐Processed Non‐polymeric Organic Photodiodes
Publisher: Wiley
Date: 29-09-2014
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.
Direct observation of trap-assisted recombination in organic photovoltaic devices
Publisher: Springer Science and Business Media LLC
Date: 14-06-2021
DOI: 10.1038/S41467-021-23870-X
Abstract: Trap-assisted recombination caused by localised sub-gap states is one of the most important first-order loss mechanism limiting the power-conversion efficiency of all solar cells. The presence and relevance of trap-assisted recombination in organic photovoltaic devices is still a matter of some considerable ambiguity and debate, hindering the field as it seeks to deliver ever higher efficiencies and ultimately a viable new solar photovoltaic technology. In this work, we show that trap-assisted recombination loss of photocurrent is universally present under operational conditions in a wide variety of organic solar cell materials including the new non-fullerene electron acceptor systems currently breaking all efficiency records. The trap-assisted recombination is found to be induced by states lying 0.35-0.6 eV below the transport edge, acting as deep trap states at light intensities equivalent to 1 sun. Apart from limiting the photocurrent, we show that the associated trap-assisted recombination via these comparatively deep traps is also responsible for ideality factors between 1 and 2, shedding further light on another open and important question as to the fundamental working principles of organic solar cells. Our results also provide insights for avoiding trap-induced losses in related indoor photovoltaic and photodetector applications.
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
Improved stability of non-ITO stacked electrodes for large area flexible organic solar cells
Publisher: Elsevier BV
Date: 11-2014
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.
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.
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.
Bulk heterojunction thickness uniformity – a limiting factor in large area organic solar cells?
Publisher: Wiley
Date: 07-2015
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
Doping‐Induced Screening of the Built‐in‐Field in Organic Solar Cells: Effect on Charge Transport and Recombination
Publisher: Wiley
Date: 10-2012
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.
Heavy Water as a Probe of the Free Radical Nature and Electrical Conductivity of Melanin
Publisher: American Chemical Society (ACS)
Date: 18-11-2015
Abstract: Melanins are pigmentary macromolecules found in many locations throughout nature including plants and vertebrate animals. It was recently proposed that the predominant brown-black pigment eumelanin is a mixed ionic-electronic conductor which has led to renewed interest in its basic properties as a model bioelectronic material. This exotic hybrid electrical behavior is strongly dependent upon hydration and is closely related to the free radical content of melanin which is believed to be a mixed population of two species: the semiquinone (SQ) and a carbon-centered radical (CCR). The predominant charge carrier is the proton that is released during the formation of the SQ radical and controlled by a comproportionation equilibrium reaction. In this paper we present a combined solid-state electron paramagnetic resonance (EPR), adsorption, and hydrated conductivity study using D2O as a probe. We make specific predictions as to how the heavy isotope effect, in contrast to H2O, should perturb the comproportionation equilibrium and the related outcome as far as the electrical conductivity is concerned. Our EPR results confirm the proposed two-spin mechanism and clearly demonstrate the power of combining macroscopic measurements with observations from mesoscopic probes for the study of bioelectronic materials.
Efficient, Large Area, and Thick Junction Polymer Solar Cells with Balanced Mobilities and Low Defect Densities
Publisher: Wiley
Date: 29-09-2014
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.
Solution-processed non-polymeric organic photodiodes
Publisher: SPIE
Date: 31-08-2015
DOI: 10.1117/12.2187583
Determination of thermal and optical parameters of melanins by photopyroelectric spectroscopy
Publisher: AIP Publishing
Date: 04-08-2005
DOI: 10.1063/1.2009833
Abstract: Photopyroelectric spectroscopy (PPE) was used to study the thermal and optical properties of melanins. The photopyroelectric intensity signal and its phase were independently measured as a function of wavelength and chopping frequency for a given wavelength in the saturation part of the PPE spectrum. Equations for both the intensity and the phase of the PPE signal were used to fit the experimental results. From these fits we obtained for the first time, with great accuracy, the thermal diffusivity coefficient, the thermal conductivity, and the specific heat of the s les, as well as a value for the condensed phase optical gap, which we found to be 1.70eV.
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.
Efficient Nanoscale Exciton Transport in Non‐Fullerene Organic Solar Cells Enables Reduced Bimolecular Recombination of Free Charges
Publisher: Wiley
Date: 05-2023
Abstract: The highest‐efficiency organic photovoltaic (OPV)‐based solar cells, made from blends of electron‐donating and electron‐accepting organic semiconductors, are often characterized by strongly reduced (non‐Langevin) bimolecular recombination. Although the origins of the reduced recombination are debated, mechanisms related to the charge‐transfer (CT) state and free‐carrier encounter dynamics controlled by the size of donor and acceptor domains are proposed as underlying factors. Here, a novel photoluminescence‐based probe is reported to accurately quantify the donor–acceptor domain size in OPV blends. Specifically, the domain size is measured in high‐efficiency non‐fullerene acceptor (NFA) systems and a comparative conventional fullerene system. It is found that the NFA‐based blends form larger domains but that the expected reductions in bimolecular recombination attributed to the enhanced domain sizes are too small to account for the observed reduction factors. Further, it is shown that the reduction of bimolecular recombination is correlated to enhanced exciton dynamics within the NFA domains. This indicates that the processes responsible for efficient exciton transport also enable strongly non‐Langevin recombination in high‐efficiency NFA‐based solar cells with low‐energy offsets.
Megawatt‐scale solar variability study: an experience from a 1.2 MWp photovoltaic system in Australia over three years
Publisher: Institution of Engineering and Technology (IET)
Date: 22-06-2016
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.
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.
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.
Hydration-controlled X-band EPR spectroscopy: A tool for unravelling the complexities of the solid-state free radical in eumelanin
Publisher: American Chemical Society (ACS)
Date: 19-04-2013
DOI: 10.1021/JP401615E
Abstract: Melanin, the human skin pigment, is found everywhere in nature. Recently it has gained significant attention for its potential bioelectronic properties. However, there remain significant obstacles in realizing its electronic potential, in particular, the identity of the solid-state free radical in eumelanin, which has been implicated in charge transport. We have therefore undertaken a hydration-controlled continuous-wave electron paramagnetic resonance study on solid-state eumelanin. Herein we show that the EPR signal from solid-state eumelanin arises predominantly from a carbon-centered radical but with an additional semiquinone free radical component. Furthermore, the spin densities of both of these radicals can be manipulated using water and pH. In the case of the semiquinone radical, the comproportionation reaction governs the pH- and hydration-dependent behavior. In contrast, the mechanism underlying the carbon-centered radical's pH- and hydration-dependent behavior is not clear consequently, we have proposed a new destacking model in which the intermolecular structure of melanin is disordered due to π-π destacking, brought about by the addition of water or increased pH, which increases the proportion of semiquinone radicals via the comproportionation reaction.
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.
A Universal Urbach Rule for Disordered Organic Semiconductors
Publisher: Research Square Platform LLC
Date: 24-02-2021
DOI: 10.21203/RS.3.RS-106584/V1
Abstract: In crystalline semiconductors, the sharpness of the absorption spectrum onset is characterized by temperature-dependent Urbach energies. These energies quantify the static, structural disorder causing localized exponential tail states, and the dynamic disorder due to electron-phonon scattering. The applicability of this exponential-tail model to molecular and amorphous solids has long been debated. Nonetheless, exponential fittings are routinely applied to the analysis of the sub-gap absorption of organic semiconductors alongside Gaussian-like spectral line-shapes predicted by non-adiabatic Marcus theory. Herein, we elucidate the sub-gap spectral line-shapes of organic semiconductors and their blends by temperature-dependent quantum efficiency measurements in photovoltaic structures. We find that the Urbach energy associated with singlet excitons universally equals the thermal energy regardless of static disorder. These observations are consistent with absorption spectra obtained from a convolution of Gaussian density of excitonic states weighted by a Boltzmann factor. A generalized Marcus charge transfer model is presented that explains the absorption spectral line-shape of disordered molecular matrices, and we also provide a simple strategy to determine the excitonic disorder energy. Our findings elaborate the true meaning of the dynamic Urbach energy in molecular solids and deliver a way of relating the photo-physics to static disorder, crucial for optimizing molecular electronic devices such as organic solar cells.
Enhancing the Properties of Ruthenium Dyes by Dendronization
Publisher: American Chemical Society (ACS)
Date: 29-05-2009
DOI: 10.1021/CM900838B
Postsynthesis Stabilization of Free-standing Mesoporous Silica Films
Publisher: American Chemical Society (ACS)
Date: 03-2004
DOI: 10.1021/LA035788O
Abstract: Mixed ammonia-water vapor postsynthesis treatment provides a simple and convenient method for stabilizing mesostructured silica films. X-ray diffraction, transmission electron microscopy, nitrogen adsorption/desorption, and solid-state NMR (13C, 29Si) were applied to study the effects of mixed ammonia-water vapor at 90 degrees C on the mesostructure of the films. An increased cross-linking of the silica network was observed. Subsequent calcination of the silica films was seen to cause a bimodal pore-size distribution, with an accompanying increase in the volume and surface area ratios of the primary (d = 3 nm) to secondary (d = 5-30 nm) pores. Additionally, mixed ammonia-water treatment was observed to cause a narrowing of the primary pore-size distribution. These findings have implications for thin film based applications and devices, such as sensors, membranes, or surfaces for heterogeneous catalysis.
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
Holographic digital Fourier microscopy for selective imaging of biological tissue
Publisher: Wiley
Date: 2004
DOI: 10.1002/IMA.20031
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
P2X7 receptor knockout mice display less aggressive biting behaviour correlating with increased brain activation in the piriform cortex
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.NEULET.2019.134575
Abstract: P2X
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
Towards structure–property–function relationships for eumelanin
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B511922G
Hydrothermal seeded synthesis of mesoporous titania for application in dye-sensitised solar cells (DSSCs)
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B406286H
Pentacene/K12 solar cells formed by organic vapor phase deposition
Publisher: SPIE-Intl Soc Optical Eng
Date: 08-08-2014
On the Impact of Cadmium Sulfide Layer Thickness on Kesterite Photodetector Performance
Publisher: Wiley
Date: 25-07-2023
Abstract: Kesterites are currently viewed as one of the most promising candidates for earth abundant and benign elements to substitute critical raw materials in photovoltaic technologies and may also be suitable for low‐noise, room‐temperature, self‐powered photodetectors. However, while the impact of buffer layers on kesterite solar cell efficiency has been an active area of investigation, links between photodetector performance and intermediate layers are yet to be addressed. Herein, the impact of cadmium sulfide buffer layers on the performance of kesterite (Cu 2 ZnSnS 4 ) photodetectors is probed. Specifically, the effect of buffer layer thickness on various photodetector performance metrices is clarified, including noise current, spectral responsivity, noise equivalent power, frequency response, and specific detectivity. Devices with a 100 nm cadmium sulfide layer perform the best, achieving a linear dynamic range of 180 dB and frequency responses in the range of tens of kHz. The key loss mechanisms are identified, and it is found that the photodetector performance to be primarily limited by shunt resistance‐induced thermal noise and defect‐induced nonradiative losses. Furthermore, we estimate the upper radiative limit of specific detectivity to be approximately Jones. Our results highlight the potential of kesterites to be used as an interesting earth abundant candidate for photodetection applications.
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.
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.
Time-independent charge carrier mobility in a model polymer:fullerene organic solar cell
Publisher: Elsevier BV
Date: 2015
Optical scatter imaging using digital Fourier microscopy
Publisher: IOP Publishing
Date: 16-09-2005
A Two-Step Sol–Gel Method for Synthesis of Nanoporous TiO<SUB>2</SUB>
Publisher: American Scientific Publishers
Date: 03-2004
DOI: 10.1166/JNN.2004.037
Abstract: This article reports a study of the effects of synthesis parameters on the preparation and formation of mesoporous titania nanopowders by employing a two-step sol-gel method. These materials displayed crystalline domains characteristic of anatase. The first step of the process involved the hydrolysis of titanium isopropoxide in a basic aqueous solution mediated by neutral surfactant. The solid product obtained from step 1 was then treated in an acidified ethanol solution containing the same titanium precursor to thicken the pore walls. Low pH and higher loading of the Ti precursor in step 2 produced better mesoporosity and crystallinity of titanium dioxide polymorphs. The resultant powder exhibited a high surface area (73.8 m2/g) and large pore volume (0.17 cm3/g) with uniform mesopores. These materials are envisaged to be used as precursors for mesoporous titania films as a wide band gap semiconductor in dye-sensitized nanocrystalline TiO2 solar cells.
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
A Tunable Metal–Organic Resistance Thermometer
Publisher: Wiley
Date: 14-12-2010
Parameterization of Metallic Grids on Transparent Conductive Electrodes for the Scaling of Organic Solar Cells
Publisher: Wiley
Date: 03-05-2021
Abstract: Intense research interest in organic photovoltaic (OPV) devices has resulted in steadily improving figures of merit in recent years. Typically, these devices are fabricated by processing active and buffer layers on transparent conductive electrodes (TCEs). Superlative OPV devices are small ( ≈0.1 cm 2 ). The sheet resistance of available monolithic transparent conductive oxide (TCO) materials limits the performance of larger devices and hence the practically attainable cell area. Here, the use of metallic grids in combination with TCOs to create composite TCEs as a means of scaling solution‐processed photovoltaics devices to practical sizes is parameterized. Finite element modeling is used to investigate the relevant design parameters and to estimate figures of merit for realistic organic solar cells. It is shown that the scalability of devices with metallic grids improves significantly when grids are implemented at micrometer scales. Representative silver grids are fabricated and the optical and electrical properties of the resulting structures are measured. Overall, these findings indicate that metallic grids can be designed to develop large‐area solution‐processed solar cells with currently available fabrication techniques.
Competition between superconductivity and weak localization in metal-mixed ion-implanted polymers
Publisher: American Physical Society (APS)
Date: 29-04-2010
Author Correction: Charge-generating mid-gap trap states define the thermodynamic limit of organic photovoltaic devices
Publisher: Springer Science and Business Media LLC
Date: 04-01-2021
DOI: 10.1038/S41467-020-20626-X
Abstract: A Correction to this paper has been published: 0.1038/s41467-020-20626-x
Unlocking the full potential of light emitting field-effect transistors by engineering charge injection layers
Publisher: Elsevier BV
Date: 11-2013
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.
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).
Scaling Considerations for Organic Photovoltaics for Indoor Applications
Publisher: Wiley
Date: 14-05-2022
Abstract: Organic semiconductor‐based photovoltaic (OPV) devices have many properties that make them attractive for indoor applications, such as tailorable light absorption, low embodied energy manufacturing and cost, structural conformality, and low material toxicity. Compared to their use as organic solar cells (OSCs) for standard outdoor solar harvesting, indoor OPV (IOPV) devices operate at low light intensities, and thus demonstrate different area‐scaling behavior. In particular, it appears as though the performance of large‐area IOPV devices is much less affected by the sheet resistances of the transparent conductive electrodes (a major limit in OSCs), but instead by factors such as their shunt resistance at low light intensities. Herein, the key parameters for improving the efficiency of large‐area IOPV using drift–diffusion and finite element modeling (FEM) are examined. The scaling behavior at low‐light intensities is theoretically and experimentally probed and demonstrated using the model PM6:Y6 system. The implications for the fabrication of large‐area devices and the requirements for high shunt resistances for low‐light performance are examined. These new insights present a clear route toward realizing monolithic large‐area organic photovoltaic cells for indoor applications – which is a necessary technical step to practical implementation.
Effect of Dimerization on Vibrational Spectra of Eumelanin Precursors
Publisher: Wiley
Date: 05-2008
DOI: 10.1111/J.1751-1097.2007.00273.X
Abstract: We have synthesized a compound ideally suited to the study of structure-function relationships in eumelanin synthesis. N-methyl-5-hydroxy-6-methoxy-indole (MHMI) has key functional groups strategically placed on the indole framework to hinder binding in the 2, 5, 6 and 7 positions. Thus, the dimer bound exclusively in the 4-4' positions was isolated and characterized. In order to study the difference in vibrational structure between the MHMI monomer and dimer, Raman spectra were acquired of both compounds, as well as indole, indole-2-carboxylic acid and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Peaks were assigned to particular vibrational modes using B3LYP density functional theory calculations, and experimental and theoretical spectra displayed good agreement. Addition of functional groups to either benzene or pyrrole rings in the indole framework impacted vibrational spectra attributed to vibrations in either ring, and in some cases, peaks appearing unchanged between two compounds corresponded to different contributing vibrations. Dimerization resulted in an expected increase in the number of vibrational modes, but not a significant increase in the number of apparent peaks, as several modes frequently contributed to an in idual observed peak. Comparison of spectral features of the monomer and dimer provides insight into eumelanin photochemistry, but final conclusions depend on the planarity of oligomeric structure in vivo.
Hybrid Nanowire Ion-to-Electron Transducers for Integrated Bioelectronic Circuitry
Publisher: American Chemical Society (ACS)
Date: 05-01-2017
DOI: 10.1021/ACS.NANOLETT.6B04075
Abstract: A key task in the emerging field of bioelectronics is the transduction between ionic rotonic and electronic signals at high fidelity. This is a considerable challenge since the two carrier types exhibit intrinsically different physics and are best supported by very different materials types-electronic signals in inorganic semiconductors and ionic rotonic signals in organic or bio-organic polymers, gels, or electrolytes. Here we demonstrate a new class of organic-inorganic transducing interface featuring semiconducting nanowires electrostatically gated using a solid proton-transporting hygroscopic polymer. This model platform allows us to study the basic transducing mechanisms as well as deliver high fidelity signal conversion by tapping into and drawing together the best candidates from traditionally disparate realms of electronic materials research. By combining complementary n- and p-type transducers we demonstrate functional logic with significant potential for scaling toward high-density integrated bioelectronic circuitry.
Optimized multilayer indium-free electrodes for organic photovoltaics
Publisher: Wiley
Date: 09-10-2014
Analysis of yearlong performance of differently tilted photovoltaic systems in Brisbane, Australia
Publisher: Elsevier BV
Date: 10-2013
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.
High-Mobility, Heterostructure Light-Emitting Transistors and Complementary Inverters
Publisher: American Chemical Society (ACS)
Date: 10-2014
DOI: 10.1021/PH500300N
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
Controlling hierarchy in solution-processed polymer solar cells based on crosslinked P3HT
Publisher: Wiley
Date: 07-08-2013
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.
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.
Fluorescent carbazole dendrimers for the detection of nitroaliphatic taggants and accelerants
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM32072J
Microglial cell hyper-ramification and neuronal dendritic spine loss in the hippocampus and medial prefrontal cortex in a mouse model of PTSD
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.BBI.2019.05.042
Abstract: Few animal models exist that successfully reproduce several core associative and non-associative behaviours relevant to post-traumatic stress disorder (PTSD), such as long-lasting fear reactions, hyperarousal, and subtle attentional and cognitive dysfunction. As such, these models may lack the face validity required to adequately model pathophysiological features of PTSD such as CNS grey matter loss and neuroinflammation. Here we aimed to investigate in a mouse model of PTSD whether contextual fear conditioning associated with a relatively high intensity footshock exposure induces loss of neuronal dendritic spines in various corticolimbic brain regions, as their regression may help explain grey matter reductions in PTSD patients. Further, we aimed to observe whether these changes were accompanied by alterations in microglial cell number and morphology, and increased expression of complement factors implicated in the mediation of microglial cell-mediated engulfment of dendritic spines. Adult male C57Bl6J mice were exposed to a single electric footshock and subsequently underwent phenotyping of various PTSD-relevant behaviours in the short (day 2-4) and longer-term (day 29-31). 32 days post-exposure the brains of these animals were subjected to Golgi staining of dendritic spines, microglial cell Iba-1 immunohistochemistry and immunofluorescent staining of the complement factors C1q and C4. Shock exposure promoted a lasting contextual fear response, decreased locomotor activity, exaggerated acoustic startle responses indicative of hyperarousal, and a short-term facilitation of sensorimotor gating function. The shock triggered loss of dendritic spines on pyramidal neurons was accompanied by increased microglial cell number and complexity in the medial prefrontal cortex and dorsal hippoc us, but not in the amygdala. Shock also increased expression of C1q in the pyramidal layer of the CA1 region of the hippoc us but not in other brain regions. The present study further elaborates on the face and construct validity of a mouse model of PTSD and provides a good foundation to explore potential molecular interactions between microglia and dendritic spines.
Immobilisation of electroactive macrocyclic complexes within titania films
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B505917H
Abstract: The 4-carboxyphenyl-appended macrocyclic ligand trans-6,13-dimethyl-6-((4-carboxybenzyl)amino)-1,4,8,11-tetraazacyclotetradecane-6-amine (HL10) has been synthesised and complexed with Co(III). The mononuclear complexes [Co(HL10)(CN)]2+ and [CoL10(OH)]+ have been prepared and the crystal structures of their perchlorate salts are presented, where the ligand is bound in a pentadentate mode in each case while the 4-carboxybenzyl-substituted pendent amine remains free from the metal. The cyano-bridged dinuclear complex [CoL10-mu-NC-Fe(CN)5]2- was also prepared and chemisorbed on titania-coated ITO conducting glass. The adsorbed complex is electrochemically active and cyclic voltammetry of the modified ITO working electrode in both water and MeCN solution was undertaken with simultaneous optical spectroscopy. This experiment demonstrates that reversible electrochemical oxidation of the Fe(II) centre is coupled with rapid changes in the optical absorbance of the film.
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
The Photoreactive Free Radical in Eumelanin
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-03-2018
Abstract: We demonstrate experimentally for the first time the presence of two free radicals in the pigment eumelanin.
2-Methoxy-6-methyl-3-nitro-4-(2-nitroprop-1-enyl)phenyl acetate
Publisher: International Union of Crystallography (IUCr)
Date: 14-05-2005
Explosive Sensing with Fluorescent Dendrimers: The Role of Collisional Quenching
Publisher: American Chemical Society (ACS)
Date: 14-09-2010
DOI: 10.1021/CM1020355
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.
A Low‐Temperature Batch Process for the Deposition of High‐Quality Conformal Alumina Thin Films for Electronic Applications
Publisher: Wiley
Date: 20-04-2023
Abstract: High‐quality, alumina thin films are extensively used as dielectrics, passivation layers, and barrier layers in electronics and many other applications. However, to achieve optimum stoichiometry and thus performance, the layers are often grown at elevated temperatures ( °C) using techniques such as atomic layer deposition (ALD). This is problematic for substrates or structures with low thermal budgets. Herein, alumina thin films are grown on 200 mm silicon substrates employing a versatile deposition method known as MVD at low deposition temperatures (35–150 °C). The chemical composition of the resulting films is investigated postdeposition using X‐ray photoelectron spectroscopy (XPS) and variable angle spectroscopic ellipsometry, with fully stoichiometric Al 2 O 3 achieved at deposition temperatures as low as 100 °C. Dielectric measurements confirm outstanding dielectric properties compared to typical thermal ALD layers deposited at much higher temperatures. This low‐temperature deposition performance by considering the MVD reactor design and the “pump‐type” regime of precursor delivery versus the “flow‐type” regime of ALD is rationalized and understood. The results clearly demonstrate that alumina thin films grown with MVD are highly versatile for electronic applications and are of particular relevance and interest for the high‐volume processing of dielectric, passivation, and barrier layers at low temperatures.
An all-solid-state biocompatible ion-to-electron transducer for bioelectronics
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7MH00831G
Abstract: The first all solid state organic electrochemical transistor based upon the skin pigment melanin.
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.
Mesostructured Dye‐Doped Titanium Dioxide for Micro‐Optoelectronic Applications
Publisher: Wiley
Date: 06-06-2003
Abstract: Optically transparent, mesostructured titanium dioxide thin films were fabricated using an hiphilic poly(alkylene oxide) block copolymer template in combination with retarded hydrolysis of a titanium isopropoxide precursor. Prior to calcination, the films displayed a stable hexagonal mesophase and high refractive indices (1.5 to 1.6) relative to mesostructured silica (1.43). After calcination, the hexagonal mesophase was retained with surface areas > 300 m2 g-1. The dye Rhodamine 6G (commonly used as a laser dye) was incorporated into the copolymer micelle during the templating process. In this way, novel dye-doped mesostructured titanium dioxide films were synthesised. The copolymer not only directs the film structure, but also provides a solubilizing environment suitable for sustaining a high monomer-to-aggregate ratio at elevated dye concentrations. The dye-doped films displayed optical thresholdlike behaviour characteristic of lified spontaneous emission. Soft lithography was successfully applied to micropattern the dye-doped films. These results pave the way for the fabrication and demonstration of novel microlaser structures and other active optical structures. This new, high-refractive index, mesostructured, dye-doped material could also find applications in areas such as optical coatings, displays and integrated photonic devices.
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.
Morphology of All-Solution-Processed "Bilayer" Organic Solar Cells
Publisher: Wiley
Date: 09-12-2011
Electric Field and Mobility Dependent First-Order Recombination Losses in Organic Solar Cells
Publisher: Wiley
Date: 07-11-2017
Importance of spectrally invariant broadband attenuation of light in indoor photovoltaic characterization
Publisher: AIP Publishing
Date: 09-2023
DOI: 10.1063/5.0159289
Efficient and bright polymer light emitting field effect transistors
Publisher: Elsevier BV
Date: 02-2015
Gaseous Adsorption in Melanins: Hydrophilic Biomacromolecules with High Electrical Conductivities
Publisher: American Chemical Society (ACS)
Date: 11-11-2009
DOI: 10.1021/LA901290F
Abstract: The melanins are an important class of multifunctional biomacromolecules that possess a number of intriguing physical and chemical properties including electrical and photoconductivity. Unusually for a conducting organic material, eumelanin is hydrophilic and its electrical properties are strongly dependent on its hydration state. We have therefore measured adsorption isotherms for two polar adsorbates, water and ethanol, in the pressed powder pellets of synthetic eumelanin typically used in electrical studies. We show that a simple kinetic monolayer Langmuir model describes the adsorption and find that there are strong adsorbate-eumelanin interactions in both cases. These isotherms allow the proper scaling of electrical conductivity data and in doing so make progress toward a better understanding of eumelanin electrical properties, which is a critical prerequisite to the design of new eumelanin-like bioelectronic materials.
Charge transport and recombination in heterostructure organic light emitting transistors
Publisher: Elsevier BV
Date: 10-2015
Interactions between cannabidiol and Δ9-THC following acute and repeated dosing: Rebound hyperactivity, sensorimotor gating and epigenetic and neuroadaptive changes in the mesolimbic pathway
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.EURONEURO.2016.12.004
Abstract: The evidence base for the use of medical cannabis preparations containing specific ratios of cannabidiol (CBD) and Δ
Synthesis and polymerization studies of organic-soluble eumelanins
Publisher: Wiley
Date: 12-02-2008
DOI: 10.1111/J.1751-1097.2007.00295.X
Abstract: The isolation, structure determination and chemical characterization of eumelanins has been plagued by their very low solubility in organic solvents. To gain insights into the structure and reactivity of these unusual and important biologic macromolecules and to pave the way for their use in electronics, we have prepared soluble melanins via the synthesis of monomeric precursors containing lipophilic substituents. Two such monomers derived from 5,6-dihydroxyindole-2-carboxylic acid (DHICA) were prepared, namely the benzyl and octyl ester derivatives. Both benzyl and octyl ester monomers were oxidatively polymerized to yield dark, melanin-like pigments. These polymerization processes were followed by UV-visible, fluorescence and NMR spectroscopy. These studies showed that the polymerizations proceeded by cross-linking at the 4- and 7-positions of the indole nucleus and led to highly heterogeneous polymeric products. Incorporation of a lipophilic benzyl or octyl group resulted in enhanced solubility of the pigments in a wide range of organic solvents. The UV-visible spectra of the organically soluble synthetic melanins were essentially identical to that of natural eumelanin.
A composite neonatal adverse outcome indicator using population-based data: an update
Publisher: Swansea University
Date: 13-08-2020
Abstract: Introduction Severe morbidity rates in neonates can be estimated using diagnosis and procedure coding in linked routinely collected data as a cost-effective way to monitor quality and safety of perinatal services. Coding changes necessitate an update to the previously published composite neonatal adverse outcome indicator for identifying infants with severe morbidity. Objectives To update the neonatal adverse outcome indicator for identifying neonates with severe morbidity, and to investigate the validity of the updated indicator. Methods We audited diagnosis and procedure codes and used expert clinician input to update the components of the indicator. We used linked birth, hospital and death data for neonates born alive at 24 weeks or more in New South Wales, Australia (2002–2014) to investigate the incidence of severe neonatal morbidity and assess the validity of the updated indicator. Results The updated indicator included 28 diagnostic and procedure components. In our population of 1,194,681 live births, 5.44% neonates had some form of morbidity. The relative risk of morbidity was greater for higher risk pregnancies and was lowest at 39–40 weeks’ gestation. Incidence increased over the study period for overall neonatal morbidity, and for in idual components intravenous infusion, respiratory diagnoses, and non-invasive ventilation. Severe neonatal morbidity was associated with double the risk of hospital readmission and ten times the risk of death within the first year of life. Conclusions The updated composite indicator has maintained concurrent and predictive validity and is a standardised, economic way to measure neonatal morbidity when using population-based data. Changes within in idual components should be considered when examining longitudinal data.
Narrow band green organic photodiodes for imaging
Publisher: Elsevier BV
Date: 11-2014
Factors Influencing the Efficiency of Current Collection in Large Area, Monolithic Organic Solar Cells
Publisher: Wiley
Date: 23-07-2012
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.
Survey of Australian’s knowledge, perception and use of cannabis for medicinal purposes
Publisher: Avens Publishing Group
Date: 30-06-2017
Superconductivity in metal-mixed ion-implanted polymer films
Publisher: AIP Publishing
Date: 09-10-2006
DOI: 10.1063/1.2358190
Abstract: Ion implantation of normally insulating polymers offers an alternative to depositing conjugated organics onto plastic films to make electronic circuits. We used a 50keV nitrogen ion beam to mix a thin 10nm Sn∕Sb alloy film into the subsurface of polyetheretherketone and report the low temperature properties of this material. We observed metallic behavior, and the onset of superconductivity below 3K. There are strong indications that the superconductivity does not result from a residual thin film of alloy, but instead from a network of alloy grains coupled via a weakly conducting, ion-beam carbonized polymer matrix.
Electronic and optoelectronic materials and devices inspired by nature
Publisher: IOP Publishing
Date: 14-02-2013
DOI: 10.1088/0034-4885/76/3/034501
Abstract: Inorganic semiconductors permeate virtually every sphere of modern human existence. Micro-fabricated memory elements, processors, sensors, circuit elements, lasers, displays, detectors, etc are ubiquitous. However, the dawn of the 21st century has brought with it immense new challenges, and indeed opportunities-some of which require a paradigm shift in the way we think about resource use and disposal, which in turn directly impacts our ongoing relationship with inorganic semiconductors such as silicon and gallium arsenide. Furthermore, advances in fields such as nano-medicine and bioelectronics, and the impending revolution of the 'ubiquitous sensor network', all require new functional materials which are bio-compatible, cheap, have minimal embedded manufacturing energy plus extremely low power consumption, and are mechanically robust and flexible for integration with tissues, building structures, fabrics and all manner of hosts. In this short review article we summarize current progress in creating materials with such properties. We focus primarily on organic and bio-organic electronic and optoelectronic systems derived from or inspired by nature, and outline the complex charge transport and photo-physics which control their behaviour. We also introduce the concept of electrical devices based upon ion or proton flow ('ionics and protonics') and focus particularly on their role as a signal interface with biological systems. Finally, we highlight recent advances in creating working devices, some of which have bio-inspired architectures, and summarize the current issues, challenges and potential solutions. This is a rich new playground for the modern materials physicist.
High quality shadow masks for top contact organic field effect transistors using deep reactive ion etching
Publisher: IOP Publishing
Date: 28-06-2010
A Narrow Optical Gap Small Molecule Acceptor for Organic Solar Cells
Publisher: Wiley
Date: 03-09-2012
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.
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
Preparation of metal mixed plastic superconductors: Electrical properties of tin-antimony thin films on plastic substrates
Publisher: AIP Publishing
Date: 05-2009
DOI: 10.1063/1.3123803
Abstract: Metal mixed polymers are a cheap and effective way to produce flexible metals and superconductors. As part of an on-going effort to learn how to tune the properties of these systems with ion implantation, we present a study of the electrical properties of these systems prior to metal mixing. We show that the electrical properties of tin-antimony thin films are remarkably robust to variations in the substrate morphology. We demonstrate that the optical absorbance of the films at a fixed wavelength provides a reliable and reproducible characterization of the relative film thickness. We find that as the film thickness is reduced, the superconducting transition in the unimplanted thin films is broadened, but the onset of the transition remains at ∼3.7 K, the transition temperature of bulk Sn. This is in marked contrast to the behavior of metal mixed films, which suggests that the metal mixing process has a significant effect on the physics of the superconducting state beyond that achieved by reducing the film thickness alone.
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.
Broadband Photon-harvesting Biomolecules for Photovoltaics
Publisher: Wiley
Date: 05-08-2006
New Type II Catechol-Thiophene Sensitizers for Dye-Sensitized Solar Cells
Publisher: American Chemical Society (ACS)
Date: 16-09-2010
DOI: 10.1021/JP105687Z
Mid-gap trap state-mediated dark current in organic photodiodes
Publisher: Springer Science and Business Media LLC
Date: 23-03-2023
DOI: 10.1038/S41566-023-01173-5
Abstract: Photodiodes are ubiquitous in industry and consumer electronics. Constantly emerging new applications for photodiodes demand different mechanical and optoelectronic properties from those provided by conventional inorganic-based semiconductor devices. This has stimulated considerable interest in the use of organic semiconductors, which provide a vast palette of available optoelectronic properties, can be incorporated into flexible form factor geometries, and promise low-cost, low-embodied energy manufacturing from earth-abundant materials. The sensitivity of a photodiode depends critically on the dark current. Organic photodiodes (OPDs), however, are characterized by a much higher dark current than expected for thermally excited radiative transitions. Here we show that the dark saturation current in OPDs is fundamentally limited by mid-gap trap states. This new insight is generated by the universal trend observed for the dark saturation current of a large set of OPDs and further substantiated by sensitive external-quantum-efficiency- and temperature-dependent current measurements. Based on this insight, an upper limit for the specific detectivity is established. A detailed understanding of the origins of noise in any detector is fundamental to defining performance limitations and thus is critical to materials and device selection, and design and optimization for all applications. Our work establishes these important principles for OPDs.
Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes
Publisher: Informa UK Limited
Date: 23-03-2015
Formation of mesostructured titania thin films using isopropoxide precursors
Publisher: Elsevier BV
Date: 04-2004
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.
Sensing nitroaromatic analytes with a bifluorene-cored dendrimer
Publisher: SPIE
Date: 20-08-2009
DOI: 10.1117/12.825821
Diffusion of nitroaromatic vapours into fluorescent dendrimer films for explosives detection
Publisher: Elsevier BV
Date: 04-2015
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.
Retrieval of the Complete Coding Sequence of the UK-Endemic Tatenale Orthohantavirus Reveals Extensive Strain Variation and Supports its Classification as a Novel Species
Publisher: Cold Spring Harbor Laboratory
Date: 16-11-2019
DOI: 10.1101/844340
Abstract: Hantaviruses are a erse group of single-stranded, negative-sensed RNA viruses, known to cause sporadic outbreaks of potentially fatal human disease. To date, only two Orthohantavirus species have been detected in the UK - Seoul virus and Tatenale. Whilst Seoul is known to be pathogenic in humans, only partial fragments of Tatenale have been recovered, precluding any accurate analysis of its phylogeny or potential pathogenicity. To overcome this shortfall we used a degenerate primer PCR method to identify Tatenale-infection in rodents living in two separate locations in the UK. PCR positive s les were then subjected to either unbiased high-throughput sequencing or overlapping PCR product sequencing to recover the complete coding sequence of the Tatenale virus. This analysis provided in-depth insight into the evolutionary origins of this recently identified UK Orthohantavirus and unequivocally showed that Tatenale virus meets the established criteria for classification as a novel species. Crucially, our data will facilitate in vitro investigation into the zoonotic potential of Tatenale virus.
Charge-generating mid-gap trap states define the thermodynamic limit of organic photovoltaic devices
Publisher: Springer Science and Business Media LLC
Date: 04-11-2020
DOI: 10.1038/S41467-020-19434-0
Abstract: Detailed balance is a cornerstone of our understanding of artificial light-harvesting systems. For next generation organic solar cells, this involves intermolecular charge-transfer (CT) states whose energies set the maximum open circuit voltage V OC . We have directly observed sub-gap states significantly lower in energy than the CT states in the external quantum efficiency spectra of a significant number of organic semiconductor blends. Taking these states into account and using the principle of reciprocity between emission and absorption results in non-physical radiative limits for the V OC . We propose and provide compelling evidence for these states being non-equilibrium mid-gap traps which contribute to photocurrent by a non-linear process of optical release, upconverting them to the CT state. This motivates the implementation of a two-diode model which is often used in emissive inorganic semiconductors. The model accurately describes the dark current, V OC and the long-debated ideality factor in organic solar cells. Additionally, the charge-generating mid-gap traps have important consequences for our current understanding of both solar cells and photodiodes – in the latter case defining a detectivity limit several orders of magnitude lower than previously thought.
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
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.
Assessing the sensing limits of fluorescent dendrimer thin films for the detection of explosive vapors
Publisher: Elsevier BV
Date: 02-2017
Role of semiconductivity and ion transport in the electrical conduction of melanin
Publisher: Proceedings of the National Academy of Sciences
Date: 21-05-2012
Abstract: Melanins are pigmentary macromolecules found throughout the biosphere that, in the 1970s, were discovered to conduct electricity and display bistable switching. Since then, it has been widely believed that melanins are naturally occurring amorphous organic semiconductors. Here, we report electrical conductivity, muon spin relaxation, and electron paramagnetic resonance measurements of melanin as the environmental humidity is varied. We show that hydration of melanin shifts the comproportionation equilibrium so as to dope electrons and protons into the system. This equilibrium defines the relative proportions of hydroxyquinone, semiquinone, and quinone species in the macromolecule. As such, the mechanism explains why melanin at neutral pH only conducts when “wet” and suggests that both carriers play a role in the conductivity. Understanding that melanin is an electronic-ionic hybrid conductor rather than an amorphous organic semiconductor opens exciting possibilities for bioelectronic applications such as ion-to-electron transduction given its biocompatibility.
Solvochromic Effects in Model Eumelanin Compounds†
Publisher: Wiley
Date: 07-02-2008
DOI: 10.1111/J.1751-1097.2007.00290.X
Abstract: We have created an indolic compound which is ideally suited to the study of the relationship between structure and function in eumelanin formation. N-methyl-5-hydroxy-6-methoxyindole (MHMI) is stable in solid and liquid states, highly soluble in a variety of solvents and forms a dimer only through the 4-4' positions. The limited binding possibilities are due to functional groups strategically placed to inhibit chemical interactions through the 2 and 7 positions. It forms a crystal structure with a remarkable packing arrangement, with four monomers grouped in parallel pairs spaced 3.5 A apart within each unit cell. Optical spectra reveal a multi-peaked absorbance profile similar to 5,6-dihydroxyindole (DHI) and N-acetyl-tryptophanamide (NATA), and strong fluorescence emission with radiative quantum yields of 29% and 33% in benzene and acetonitrile, respectively. The quantum yield is similar to that of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and shows that solvent aromaticity by itself does not affect the yield. Solution in chloroform results in an almost complete quenching of the fluorescence but an increase in emission is observed with photoactivation. Crystallographic results shown here suggest new structural possibilities for eumelanin and the controlled binding possibilities make this an excellent model for monitoring changes in function with increasing oligomer size in eumelanin formation.
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.
A universal Urbach rule for disordered organic semiconductors
Publisher: Springer Science and Business Media LLC
Date: 28-06-2021
DOI: 10.1038/S41467-021-24202-9
Abstract: In crystalline semiconductors, absorption onset sharpness is characterized by temperature-dependent Urbach energies. These energies quantify the static, structural disorder causing localized exponential-tail states, and dynamic disorder from electron-phonon scattering. Applicability of this exponential-tail model to disordered solids has been long debated. Nonetheless, exponential fittings are routinely applied to sub-gap absorption analysis of organic semiconductors. Herein, we elucidate the sub-gap spectral line-shapes of organic semiconductors and their blends by temperature-dependent quantum efficiency measurements. We find that sub-gap absorption due to singlet excitons is universally dominated by thermal broadening at low photon energies and the associated Urbach energy equals the thermal energy, regardless of static disorder. This is consistent with absorptions obtained from a convolution of Gaussian density of excitonic states weighted by Boltzmann-like thermally activated optical transitions. A simple model is presented that explains absorption line-shapes of disordered systems, and we also provide a strategy to determine the excitonic disorder energy. Our findings elaborate the meaning of the Urbach energy in molecular solids and relate the photo-physics to static disorder, crucial for optimizing organic solar cells for which we present a revisited radiative open-circuit voltage limit.
Neural correlates of interactions between cannabidiol and Δ9‐tetrahydrocannabinol in mice: implications for medical cannabis
Publisher: Wiley
Date: 18-11-2015
DOI: 10.1111/BPH.13333
Rates of neonatal morbidity by maternal region of birth and gestational age in New South Wales, Australia 2003‐2016
Publisher: Wiley
Date: 22-10-2020
DOI: 10.1111/AOGS.14012
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.
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