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Power- and Spectral-Dependent Photon-Recycling Effects in a Double-Junction Gallium Arsenide Photodiode
摘要： Photon recycling effects improve radiative efficiencies of semiconductor materials, and play important roles in the design of high performance optoelectronic devices. Conventional research mostly studies the impact of photon recycling on the voltage of photodiodes. Here we systematically analyze the photon response of a microscale gallium arsenide (GaAs) based double junction photodiode. In such a device, the current matching condition between two subcells is determined by their photon coupling. Photodynamics in the device is examined and reveals the material’s internal quantum efficiencies. By leveraging photon distributions inside the device, we discover that its photocurrent and spectral responses are highly dependent on the illumination intensity. Consistent with theoretical analyses, the device’s photocurrents exhibit linear and superlinear power dependent characteristics under near-infrared and violet-blue illuminations, respectively. Due to strongly enhanced photon recycling effects under strong illumination, broadband photon responses (external quantum efficiency close to 50% from 400 nm to 800 nm) could be achieved in such a strongly current mismatched GaAs dual junction device. The understanding of photon processes in such devices would offer routes to the design of high-performance photodetectors and solar cells.
关键词： photovoltaics,photodetectors,gallium arsenide,photon recycling,multijunction
更新于2025-09-23 15:23:52
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Challenges and opportunities for efficiency boost of next generation Cu(In,Ga)Se <sub/>2</sub> solar cells: prospect for a paradigm shift
摘要： Cu(In,Ga)Se2 photovoltaic technology has notably progressed over the past years. Power conversion efficiencies above 23% were reached in spite of the absorber polycrystalline nature. Although efficiencies are still far from the practical limits, the material quality is approaching that of III-V compounds that yield the most efficient solar cells. High carrier lifetime, low open circuit voltage deficit and external radiative efficiency in single-digit percentage range, suggest the next efficiency boost may arise from the implementation of alternative device architectures. In this perspective paper, we describe the current challenges and pathways to enhance the power conversion efficiency of Cu(In,Ga)Se2 solar cells. Specifically, we suggest the use of non-graded absorbers, integration of charge selective contacts and maximization of photon recycling. We examine these concepts by a semi-empirical device modelling approach, and show that these strategies can lead to efficiencies of 29% under the AM1.5 global spectrum. An analysis whether or not current state-of-the-art Cu(In,Ga)Se2 solar cells already benefit from photon recycling is also presented.
关键词： Cu(In,Ga)Se2,charge selective contacts,photon recycling,power conversion efficiency,solar cells
更新于2025-09-23 15:21:01
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Device physics of back-contact perovskite solar cells
摘要： Back-contact perovskite solar cells (PSCs) are a promising candidate to further increase power conversion efficiency (PCE) and have been the subject of many investigations. However their full potential has not been achieved due a lack of a complete understanding of their operation from a device physics perspective. In this study, a detailed photoelectrical model for back-contact PSCs is developed by coupling a drift-diffusion description of free charge transport model with ion migration currents and emitted-carrier generation resulting from photon recycling. By studying the influence of relevant electrical parameters, the interplay between charge generation, transport and recombination, is revealed to further clarify the design principles based on devices with a back-contact structure. Although devices featuring the back-contact structure exhibit a sensitivity to electrical parameters, a high PCE exceeding 25% is predicted if the interface passivation and perovskite film quality can be well controlled. Different conduction band and valence band offsets offer various screening opportunities for functional materials with high efficiencies are introduced. Additionally, the simulated results revealed that mobile ions degrade the device performance if the average ion concentration exceeds 1016 cm?3. Furthermore, we point out that photon recycling can effectively compensate against radiative recombination, thereby resulting in an improved open circuit voltages. The results provide a new understanding of the carrier transport dynamics, ion migration, and photon recycling effects for the back-contact structure, which can be applied to a systematic improvement in the design of high efficiency PSCs.
关键词： Power conversion efficiency,Ion migration,Back-contact perovskite solar cells,Photoelectrical model,Photon recycling
更新于2025-09-19 17:13:59
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The role of photon recycling in perovskite light-emitting diodes
摘要： Perovskite light-emitting diodes have recently broken the 20% barrier for external quantum efficiency. These values cannot be explained with classical models for optical outcoupling. Here, we analyse the role of photon recycling (PR) in assisting light extraction from perovskite light-emitting diodes. Spatially-resolved photoluminescence and electroluminescence measurements combined with optical modelling show that repetitive re-absorption and re-emission of photons trapped in substrate and waveguide modes significantly enhance light extraction when the radiation efficiency is sufficiently high. In this manner, PR can contribute more than 70% to the overall emission, in agreement with recently-reported high efficiencies. While an outcoupling efficiency of 100% is theoretically possible with PR, parasitic absorption losses due to absorption from the electrodes are shown to limit practical efficiencies in current device architectures. To overcome the present limits, we propose a future configuration with a reduced injection electrode area to drive the efficiency toward 100%.
关键词： external quantum efficiency,light-emitting diodes,photon recycling,optical outcoupling,perovskite
更新于2025-09-16 10:30:52