A5059678196- Organic Electronics and Photovoltaics
- Photovoltaic System Optimization Techniques
- Conducting polymers and applications
- Thin-Film Transistor Technologies
- solar cell performance optimization
- Organic Light-Emitting Diodes Research
- Solar Thermal and Photovoltaic Systems
- Photovoltaic Systems and Sustainability
- Perovskite Materials and Applications
- Solar Radiation and Photovoltaics
- Silicon and Solar Cell Technologies
- CCD and CMOS Imaging Sensors
- Radiation Detection and Scintillator Technologies
- Advanced Fluorescence Microscopy Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Memory and Neural Computing
- Chalcogenide Semiconductor Thin Films
- Medical Imaging Techniques and Applications
- Advanced biosensing and bioanalysis techniques
- Photoacoustic and Ultrasonic Imaging
- Semiconductor Quantum Structures and Devices
- Optical Wireless Communication Technologies
- Thermography and Photoacoustic Techniques
- ZnO doping and properties
- Force Microscopy Techniques and Applications
National Physical Laboratory
2016-2025
Centre National de la Recherche Scientifique
2014
Ben-Gurion University of the Negev
2014
Kanagawa Academy of Science and Technology
2014
Université de Bordeaux
2014
Institut Polytechnique de Bordeaux
2014
University of Potsdam
2010-2013
University of Cambridge
2005-2010
Cavendish Hospital
2009-2010
University College London
2007-2008
A "visible-blind" solution-processed UV photodetector is realized on the basis of colloidal ZnO nanoparticles. The devices exhibit low dark currents with a resistance >1 TΩ and high photocurrent efficiencies responsivity 61 A/W at an average intensity 1.06 mW/cm2 illumination 370 nm. characteristic times for rise fall are <0.1 s about 1 s, respectively. device associated light-induced desorption oxygen from nanoparticle surfaces, thus removing electron traps increasing free carrier density...
We simulate organic bulk heterojunction solar cells. The effects of energetic disorder are incorporated through a Gaussian or exponential model density states. Analytical models open-circuit voltage (${V}_{\mathrm{OC}}$) derived from the splitting quasi-Fermi potentials. Their predictions backed up by more complex numerical device simulations including such as carrier-density--dependent charge-carrier mobilities. It is predicted that V${}_{\mathrm{OC}}$ depends on: (1) donor-acceptor energy...
Charge carrier mobility is a figure of merit commonly used to rate organic semiconducting materials for their suitability in applications such as solid-state lighting or photovoltaics. Although large variations are found published values on identical materials, there little open discussion the literature reproducibility these results. We address this with an interlaboratory study measurements performed set semiconductors using space-charge limited current method. measured nominally devices...
We use the Kelvin probe method to study energy-level alignment of four conjugated polymers deposited on various electrodes. Band bending is observed in all when substrate work function exceeds critical values. Through modeling, we show that band explained by charge transfer from electrodes into a small density states extends several hundred meV gap. The energetic spread these correlated with charge-carrier mobilities, suggesting same also govern transport bulk polymers.
Time-delayed collection field (TDCF) experiments are performed on bulk heterojunction solar cells comprised of a blend poly(3-hexylthiophene) and [6,6]-phenyl C71 butyric acid methyl ester. TDCF is analogous to pump−probe experiment using optical excitation an electrical probe with resolution <100 ns. The number free charge carriers extracted after short delay found be independent the electric during illumination. Also, variable between do not reveal any evidence for generation via...
We have applied time-delayed collection field (TDCF) and charge extraction by linearly increasing voltage (CELIV) to investigate the photogeneration, transport, recombination of carriers in blends composed PCPDTBT/PC70BM processed with without solvent additive diiodooctane. The results suggest that has severe impacts on elementary processes involved photon collected electron conversion these blends. First, a pronounced dependence free carrier generation is found for both blends, where...
Bulk electron transport in a high mobility n-type polymer is studied by time-of-flight photocurrent measurements and electron-only devices. mobilities of ∼ 5×10−3 cm2/Vs are obtained. The analysis the currents suggests presence an injection barrier for all conventionally used low workfunction cathodes.
Abstract Photovoltaics (PVs) are a critical technology for curbing growing levels of anthropogenic greenhouse gas emissions, and meeting increases in future demand low-carbon electricity. In order to fulfill ambitions net-zero carbon dioxide equivalent (CO 2 eq) emissions worldwide, the global cumulative capacity solar PVs must increase by an magnitude from 0.9 TW p 2021 8.5 2050 according International Renewable Energy Agency, which is considered be highly conservative estimate. 2020, Henry...
We demonstrate that the resonant tunnel current through a double-barrier structure is sensitive to capture of single photoexcited holes by an adjacent layer quantum dots. This phenomenon could allow detection photons with low dark count rates and high efficiencies. The magnitude sensing may be controlled via thickness barriers. Larger currents give improved signal noise sub-$\ensuremath{\mu}\mathrm{s}$ photon time resolution.
Organic photodetectors for use in medical x-ray digital imaging applications are fabricated from poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester using a solution-based, temperature assisted deposition protocol. In comparison to bulk heterojunction structures, the proposed protocol leads much lower dark currents while still offering useful external quantum efficiency values. Devices made by this lead of around 50pA∕cm2 at −0.8V, well within requirements imaging. When...
We investigate the band bending that occurs at interface between a disordered organic semiconductor and metal electrode. Ultraviolet photoemission spectroscopy measurements of thin layers on conducting substrates have revealed within few nanometers interface. It has been proposed this is caused by transfer carriers from substrate into empty states in film. Here we numerically model process simulating film with given density thermal equilibrium metallic substrate. Comparing various published...
There is an increasing interest in using indoor photovoltaic (IPV) devices to power Internet of Things applications, low communications, and environmental sensing. For the commercialization IPV technologies, device performance measurements need conform relevant standardized specifications. We present a novel measurement system that incorporates digital light processing (DLP) deliver spectrally invariant source at all required illuminance levels, as specified by standard testing conditions...
In this letter, we examine the effect of charge trapping on geminate recombination and organic photovoltaic performance using a Monte Carlo model. We alter degree by considering energetic disorder to be spatially uncorrelated or correlated. On correlating disorder, so reducing trapping, it is found that power conversion efficiency blend bilayer devices improves factors 3.1 2.6, respectively. These results are related experimental data quantum chemical calculations for...
We have used space-charge limited current measurements to study the mobility of holes and electrons in two fluorene-based copolymers for temperatures from 100 300 K. Interpreting results using standard analytical model produced an Arrhenius-type temperature dependence a range only was found be apparently dependent on thickness polymer film. To improve this, we interpreted our data numerical that takes into account effects carrier concentration energetic disorder transport. This accounted...
Measured mobility and current-voltage characteristics of single layer photovoltaic (PV) devices composed poly${$9,9-dioctylfluorene-co-bis[$N,{N}^{\ensuremath{'}}$-(4-butylphenyl)]bis($N,{N}^{\ensuremath{'}}$-phenyl-1,4-phenylene)diamine$}$ (PFB) poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) have been reproduced by a mesoscopic model employing the kinetic Monte Carlo (KMC) approach. Our aim is to show how avoid uncertainties common in electrical transport models arising from need fit...
To address the nature of charge transport and origin severe (intrinsic) trapping in electron-transporting polymers, transient steady-state measurements have been conducted on prototype donor/acceptor copolymer poly[2,7-(9,9-dialkyl-fluorene)-alt-5,5-(4\ensuremath{'},7\ensuremath{'}-di-2-thienyl-2\ensuremath{'},1\ensuremath{'},3\ensuremath{'}-benzothiadiazole)] (PFTBTT). A charge-generation layer technique is used to selectively desired carrier type, perform time-of-flight samples with 200 nm...
We fabricate a type of back-contact perovskite solar cell based on 1.5 μm-width grooves that are embossed into plastic film whose opposing "walls" selectively coated with either n- or p-type contacts. A precursor solution is then deposited the grooves, creating individual photovoltaic devices. Each groove device series-connected to its neighbors, minimodules consisting hundreds connected grooves. Here, we report fabrication groove-based devices using slot-die coating deposit and explore...
The x-ray stability of photodiodes made poly(9,9-di-n-octylfluorene-co-benzothiadiazole):perylene diimide, poly[2,7-(9,9-di-n-octylfluorene)-co-(1,4-phenylene-[(4-sec-butylphenyl)imino]-1,4-phenylene)]:perylene diimide and poly(3-hexylthiophene):([6,6]-phenylC61-butyric acid methyl ester) (P3HT:PCBM) blends has been examined up to lifetime doses equivalent those used in medical digital imaging applications. Dark currents external quantum efficiencies (EQEs) are not significantly affected...
Advances in organic photovoltaics have created the opportunity for low-cost, high-throughput manufacture of solar cells using roll-to-roll printing technology; however, performance, reliability, and production yield these devices can be critically limited by incorporation defects during fabrication. The detection elimination all is unrealistic, so techniques are required to identify those types which most critical cell functionality. Here, we combine mapping both surface topography...
Transient photovoltage measurements are widely used to characterize organic solar cells, but the validity of this method has been established only in a limited range cases. The authors simulate these over broad conditions, and offer generalized for assessing validity. approach that they propose significantly extends valid measurement which ought be quite useful drive toward clean, cheap power.
We investigate charge transport in a high-electron mobility polymer, poly(N,N-bis 2-octyldodecyl-naphthalene-1,4,5,8-bis dicarboximide-2,6-diyl-alt-5,5-2,2-bithiophene) [P(NDI2OD-T2), Polyera ActivInk™ N2200]. Time-of-flight measurements reveal electron mobilities approaching those measured field-effect transistors, the highest ever recorded conjugated polymer using this technique. The modest temperature dependence and weak dispersion of transients indicate low energetic disorder material....