A5038009484- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Semiconductor Quantum Structures and Devices
- Organic Light-Emitting Diodes Research
- Thin-Film Transistor Technologies
- Perovskite Materials and Applications
- Genetic Associations and Epidemiology
- Evolutionary Algorithms and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Semiconductor Detectors and Materials
- Pancreatic function and diabetes
- solar cell performance optimization
- Photonic and Optical Devices
- Advanced Optical Sensing Technologies
- Colorectal Cancer Screening and Detection
- Gastric Cancer Management and Outcomes
- Neural dynamics and brain function
- Force Microscopy Techniques and Applications
- Silicon and Solar Cell Technologies
- Advanced Memory and Neural Computing
- Semiconductor materials and interfaces
- Chalcogenide Semiconductor Thin Films
- Colorectal Cancer Surgical Treatments
- Neural Networks and Applications
- Genetic factors in colorectal cancer
Durham University
2015-2024
St George's Hospital
2021
University of Oxford
2008-2019
Churchill Hospital
2008-2019
South West London and St George's Mental Health NHS Trust
2013-2018
St George’s University Hospitals NHS Foundation Trust
2013-2018
Vejle Sygehus
2018
St George's Hospital
2009-2015
Durham Technical Community College
2015
King's College Hospital
2014
We present a Monte Carlo model of carrier separation and recombination in nanostructured organic photovoltaic (OPV) devices which takes into account all electrostatic interactions, energetic disorder, polaronic effects. This permits detailed analysis the strong morphology dependence collection efficiency. find that performance is determined both by orientation heterojunction relative to external electric field as well confinement due polymer intermixing. The predicts an idealized...
Through controlled annealing of intimately mixed blends the polyfluorene copolymers poly(9,9'-dioctylfluorene-co-bis(N,N'-(4,butylphenyl))bis(N,N'-phenyl-1,4-phenylene)diamine) (PFB) and poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) we observe change in charge generation dynamics photovoltaic performance as length nanoscale phase separation is varied from 5 nm or less to greater than 40 nm. We find that device efficiency optimized for a ∼20 nm, significantly larger exciton diffusion...
The use of organic photovoltaics (OPVs) could reduce production costs for solar cells because these materials are solution processable and can be manufactured by roll-to-roll printing. nanoscale texture, or film morphology, the donor/acceptor blends used in most OPVs is a critical variable that dominate both performance new being optimized lab efforts to move from laboratory-scale factory-scale production. Although efficiencies have improved significantly recent years, progress morphology...
The domain size, purity and interfacial width between domains for a bulk heterojunction are controllably altered through use of Cahn–Hilliard modeling their relative effect on OPV performance is predicted using Monte Carlo modeling. It found that locally sharp, well-connected only 4 nm extent out perform morphologies with broadened interfaces and/or impure even when sizes were at the 'optimum' size ∼10 nm. More generally, these data provide information most effective method to optimize...
We investigate the rate constant for Langevin-type bimolecular recombination using a Monte Carlo model. It is found that filamentary transport, mobility anisotropy, restriction of transport in one dimension, and confinement electrons holes to transporting component within blend can cause significant deviations from classical Langevin behavior. discuss detail reasons failure model these instances, provide alternative formula, comment upon implications polymer transistors, LEDs, photovoltaics.
The effect of cascaded energy heterojunctions on geminate charge recombination in organic photovoltaic devices is examined using a kinetic Monte Carlo model. structure the heterojunction, which encourages spatial separation pair, varied to recreate that found ternary blends and tri-layers, as well formed by self-organization binary one component crystallizes. It shown substantial reductions can indeed be achieved with parameters similar reported for P3HT:PCBM solar cells. However, efficacy...
Although cancer is largely seen as a disease stemming from genetic mutations, evidence has implicated epigenetic regulation of gene expression driving force for tumorigenesis. Epigenetic by histone modification, specifically through polycomb group (PcG) proteins such EZH2 and BMI-1, major driver in stem cell biology found to be correlated with poor prognosis many tumor types. This suggests role PcG cells (CSCs). We hypothesized that modification EZH2, specifically, helps maintain the CSC...
A Monte Carlo model is used to examine geminate pair dissociation in polymer-polymer photovoltaic devices. It found that increasing one or both carrier mobilities aids separation yield eta(GS) particularly at low fields. This, turn, leads improved maximum power output from blend photovoltaics, even when are unbalanced by a factor of 10. The dynamic behaviors charges eventually separate and recombine examined for the first time. shown pairs bilayer become effectively free separated...
<h3>Abstract</h3> <h3>Objectives</h3> People with Multiple Sclerosis (MS) have a larger choroid plexus (CP) volume than healthy controls. We investigated CP in early MS by quantitatively assessing brain MRI scans patients presenting optic neuritis (ON) as clinically isolated syndrome (CIS), compared to cohort established Relapsing Remitting (RRMS) and <h3>Methods</h3> Pre- post-gadolinium 3D-T1, 3D FLAIR diffusion-weighted images were acquired from 44 CIS ON at baseline, 1, 3, 6 12 months...
Abstract Through controlled annealing of planar heterojunction (bilayer) devices based on the polyfluorene copolymers poly(9,9‐dioctylfluorene‐co‐bis(N,N′‐(4,butylphenyl))bis(N,N′‐phenyl‐1,4‐phenylene)diamine) (PFB) and poly(9,9‐dioctylfluorene‐co‐benzothiadiazole) (F8BT) we study influence interface roughness generation separation electron–hole pairs at donor/acceptor interface. Interface structure is independently characterized by resonant soft X‐ray reflectivity with interfacial width...
The insulin (INS) region is the second most important locus associated with Type 1 Diabetes (T1D). study of DNA methylation pattern 7 CpGs proximal to TSS in INS gene promoter revealed that T1D patients have a lower level CpG -19, -135 and -234 (p = 2.10−16) higher -180 than controls, while was comparable for -69, -102, -206. magnitude hypomethylation relative control population 8–15% corresponding levels controls correlated -19 (r 0.77) 0.65). 70/485 (14%) had simultaneous decrease -135,...
This Perspective discusses the physics, implementation and findings of Kinetic Monte Carlo (KMC) models applied to organic photovoltaic devices (OPVs). It is shown that KMC can relate morphology energy levels on nano-scale geminate non-geminate recombination, charge transport, injection extraction measured in macro-scale OPVs. In particular, investigations probing circumstances under which recombination is, not, a significant loss mechanism OPVs are reviewed. Furthermore, mechanisms yield...
The molecular-level origins of the effects annealing temperature and molecular weight on hole mobility in P3HT are elucidated using coarse-grained dynamics, quantum chemical calculations, kinetic Monte Carlo charge-transport simulations a variety realistic thin-film morphologies. zero-field is shown to increase as or average weights samples increased, accordance with experimental results. Crystal structure analysis shows that dependence can be attributed size structural order crystallites...
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...
In this letter we evaluate the accuracy of first reaction method (FRM) as commonly used to reduce computational complexity mesoscale Monte Carlo simulations geminate recombination and performance organic photovoltaic devices. A wide range carrier mobilities, degrees energetic disorder, applied electric field are considered. For ranges disorder relevant for most polyfluorene, polythiophene, alkoxy poly(phenylene vinylene) materials in photovoltaics, separation efficiency predicted by FRM...
We present a combined experimental and theoretical investigation into the charge transport recombination in dye-sensitized mesoporous TiO2. electronically probe photoinduced change conductivity through in-plane devices while simultaneously optically probing signatures of species. Our quasi-continuous wave technique allows us to build data sets electron mobility versus density over wide temperature range. observe that dependence TiO2 is strong at high temperatures gradually reduces with...
In this paper we use a Kinetic Monte Carlo model to examine whether hot charge transfer states are the primary cause of efficient free-charge generation in organic photovoltaic devices.
The temperature dependence of electron and hole impact ionization in gallium arsenide (GaAs) has been determined from photomultiplication measurements at temperatures between 20 K 500 K. It is found that suppressed by increasing because the increase phonon scattering. Temperature variations avalanche multiplication are shown to decrease with decreasing avalanching region width, effect interpreted terms reduced scattering correspondingly path length. Effective coefficients derived predict...
Abstract A promising, general strategy for improving performance of optoelectronic devices based on conjugated polymer semiconductors is to make better use the fast intrachain transport along covalently bonded backbone. Little known, however, about how recombination rate between electrons and holes would be affected in device structures which current flow primarily chain. Here a light‐emitting field effect transistor (LFET) structure with uniaxially aligned semiconducting used show that...
We use a Monte Carlo model to predict the effect of composition, domain size, and energetic disorder upon mobility carriers in an organic donor-acceptor blend. These simulations show that, for changes local morphology expected within thickness typical bulk heterojunction photovoltaic device, more than order magnitude are expected. The impact nonuniform space-charge-limited diode (PV) device performance is examined using drift-diffusion model. current passing through shown depend position...