A5007017822- Organic Electronics and Photovoltaics
- Perovskite Materials and Applications
- Conducting polymers and applications
- Molecular Junctions and Nanostructures
- Organic Light-Emitting Diodes Research
- Semiconductor Quantum Structures and Devices
- Chalcogenide Semiconductor Thin Films
- Quantum and electron transport phenomena
- Silicon and Solar Cell Technologies
- Solid-state spectroscopy and crystallography
- Spectroscopy and Quantum Chemical Studies
- solar cell performance optimization
- Photochemistry and Electron Transfer Studies
- Advanced Condensed Matter Physics
- Thin-Film Transistor Technologies
- Thermal Radiation and Cooling Technologies
- Microfluidic and Bio-sensing Technologies
- Quantum optics and atomic interactions
- Quantum Dots Synthesis And Properties
- 3D Printing in Biomedical Research
- Cellular Mechanics and Interactions
- Photoreceptor and optogenetics research
- Quantum Chromodynamics and Particle Interactions
- Analytical Chemistry and Sensors
- Organic and Molecular Conductors Research
Swansea University
2020-2024
Dalhousie University
2016-2019
Abstract Detailed balance is a cornerstone of our understanding 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 significantly lower in energy than CT external quantum efficiency spectra significant number semiconductor blends. Taking these into account and using principle reciprocity between emission absorption...
Abstract Poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been one of the most established hole transport layers (HTL) in organic solar cells (OSCs) for several decades. However, presence PSS − ions is known to deteriorate device performance via a number mechanisms including diffusion HTL‐active layer interface and unwanted local chemical reactions. In this study, it shown that can also result p ‐doping high efficiency donor:non‐fullerene acceptor blends – resulting...
Abstract Low‐offset organic solar cell systems have attracted great interest since nonfullerene acceptors came into the picture. While numerous studies focused on charge generation process in these low‐offset systems, only a few details of each loss channel and their impact overall device performance. Here, several are blended with same polymer donor to form series where significant variation performance is observed. Through detailed analyses pathways, it found that: i) donor:acceptor...
The strong spin-orbit interaction in the organic-inorganic perovskites tied to incorporation of heavy elements (e.g., Pb and I) makes these materials interesting for applications spintronics. In conjunction with a lack inversion symmetry associated distortions metal-halide octahedra, surfaces interfaces, or application bias, Rashba effect (used spin field-effect transistors filters) has been predicted be much larger than traditional III-V semiconductors such as GaAs. Evidence coupling...
Charge generation quantum yield of state-of-the-art non-fullerene-based organic solar cells is found to be near unity as probed by a newly developed methodology.
Abstract Solar cells incorporating organic-inorganic perovskite, which may be fabricated using low-cost solution-based processing, have witnessed a dramatic rise in efficiencies yet their fundamental photophysical properties are not well understood. The exciton binding energy, central to the charge collection process, has been subject of considerable controversy due subtleties extracting it from conventional linear spectroscopy techniques strong broadening tied disorder. Here we report...
Understanding exciton diffusion in organic solar cells is crucial to understanding the recent rise power-conversion efficiencies afforded by using non-fullerene acceptor molecules (NFAs). This study introduces a technique called pulsed-PLQY for measuring lengths semiconductors. Compared existing techniques, faster, easier, requires less specialized equipment, and sensitive experimental conditions. Using this method, authors find that modern semiconductors exhibit longer than their fullerene...
The highest-efficiency organic photovoltaic (OPV)-based solar cells, made from blends of electron-donating and electron-accepting semiconductors, are often characterized by strongly reduced (non-Langevin) bimolecular recombination. Although the origins recombination debated, mechanisms related to charge-transfer (CT) state free-carrier encounter dynamics controlled size donor acceptor domains proposed as underlying factors. Here, a novel photoluminescence-based probe is reported accurately...
Despite general agreement that the generation of free charges in organic solar cells is driven by an energetic offset, power conversion efficiencies have been improved using low-offset blends. In this work, we explore interconnected roles exciton diffusion and lifetime play charge process under various offsets. A detailed balance approach used to develop analytic framework for dissociation free-charge accounting at donor–acceptor interface. For systems, find be a pivotal component process,...
Perovksite semiconductors have shown promise for low-cost solar cells, lasers and photodetectors, yet their fundamental photophysical properties are not well understood. Recent observations of a low ($\sim$few meV) exciton binding energy evidence hot phonon effects in the room temperature phase suggest that perovskites much closer to inorganic than absorber layers traditional organic photovoltaics, signaling need experiments shed light on placement perovskite materials within spectrum used...
Non-radiative losses to the open-circuit voltage are a primary factor in limiting power conversion efficiency of organic photovoltaic devices. The dominant non-radiative loss is intrinsic active layer and can be determined from quasi-Fermi level splitting (QFLS) radiative thermodynamic limit photovoltage. Quantification QFLS thin film devices with low mobility challenging due excitonic nature photoexcitation additional sources nonradiative associated device structure. This work outlines an...
Recombination of free charges is a key loss mechanism limiting the performance organic semiconductor-based photovoltaics such as solar cells and photodetectors. The carrier density-dependence rate recombination associated coefficients are often estimated using transient charge extraction (CE) experiments. These experiments, however, neglect effect during process. In this work, validity CE experiment for low-mobility devices, photovoltaics, investigated drift-diffusion simulations. We find...
Carrier scattering processes are studied in CH3NH3PbI3 using temperature-dependent four-wave mixing experiments. Our results indicate that by ionized impurities limits the interband dephasing time (T2) below 30 K, with strong electron-phonon dominating at higher temperatures (with a scale of 125 fs 100 K). theoretical simulations provide quantitative agreement measured carrier rate and show acoustic phonon is enhanced spin-orbit coupling, which modifies band-edge density states. The Rashba...
As the world strives toward its net‐zero targets, innovative solutions are required to reduce carbon emissions across all industrial sectors. One approach that can from food production is agrivoltaics—photovoltaic devices enable dual‐use of land for both agricultural and electrical power‐generating purposes. Optimizing agrivoltaics presents a complex systems‐level challenge requiring balance between maximizing crop yields on‐site power generation. This necessitates careful consideration...
The interest in perovskite-based solar cell absorber materials has skyrocketed recent years due to the rapid rise efficiency and potential for cost reductions tied solution-processed device fabrication. Due complications associated with presence of strong static dynamic disorder these organic-inorganic materials, fundamental photophysical behavior photo-excited charge carriers remains unclear. We apply four-wave mixing spectroscopy study carrier dynamics...
The strong spin-orbit interaction in the organic-inorganic perovskites tied to incorporation of heavy elements (\textit{e.g.} Pb, I) makes these materials interesting for applications spintronics. Due a lack inversion symmetry associated with distortions metal-halide octahedra, Rashba effect (used \textit{e.g.} spin field-effect transistors and filters) has been predicted be much larger than traditional III-V semiconductors such as GaAs, supported by recent observation near record splitting...
A Correction to this paper has been published: https://doi.org/10.1038/s41467-020-20626-x
Nonradiative losses to the open-circuit voltage are a primary factor in limiting power-conversion efficiency of organic photovoltaic devices. The dominate nonradiative loss bulk is intrinsic active layer and can be determined from quasi-Fermi-level splitting (QFLS) radiative thermodynamic limit photovoltage. Quantification QFLS thin-film devices with low mobility challenging due excitonic nature photoexcitation additional sources associated device structure. This work outlines an...