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Two-Stage Ultraviolet Degradation of Perovskite Solar Cells Induced by the Oxygen Vacancy-Ti4+ States
摘要： The failure of perovskite solar cells (PSCs) under ultraviolet (UV) irradiation is a serious barrier of commercial utilization. Here, a two-stage degradation process of TiO2-based PSCs is discovered under continuous UV irradiation in an inert atmosphere. In the first decay stage, oxygen vacancy-Ti3+ (Ti3+-VO) transform into active Ti4+-VO trap states under UV excitation and cause photocarrier loss. Furthermore, Ti4+-VO states can convert back into Ti3+-VO states through oxidizing I?, which result in the accumulation of I3?. Sequentially, the rapid decomposition of perovskite accelerated by increasing I3? replaces the photocarrier loss as the dominant mechanism leading to the second decay stage. Then, a universal method is proposed to improve the UV stability by blocking the transformation of Ti3+-VO states, which can be realized by polyethyleneimine ethoxylated (PEIE) modified layer. The optimized devices remain ~75% of its initial efficiency (20.51%) under UV irradiation at 72 days, whereas the normal devices fail completely.
关键词： Ti4+ states,Oxygen vacancy,UV degradation,Perovskite solar cells,TiO2,PEIE
更新于2025-09-23 15:19:57
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Polyelectrolyte‐Doped SnO <sub/>2</sub> as a Tunable Electron Transport Layer for High‐Efficiency and Stable Perovskite Solar Cells
摘要： The charge transport layer is crucial to the performance and stability of the perovskite solar cells. Compared with other conventional metal oxide electron transport materials, SnO2 has a deeper conduction band and higher electron mobility, and can efficiently serve as an electron transport layer to facilitate charge extraction and transfer. In this study, we have reported an optimized low temperature solution processed SnO2 electron transport layer by doping PEIE polyelectrolyte into SnO2 for the first time in the perovskite solar cells. It was found that the performance of all aspects of the doped SnO2 film was improved than that of the pristine SnO2 film. The better energy level alignment, larger built-in field, enhanced electron transfer/extraction, and reduced charge recombination all contribute to the improved device performance. Finally, a perovskite solar cell with a power conversion efficiency of 20.61 % was successfully prepared under low temperature below 150 oC. Moreover, the stability of the doped SnO2-based device was also greatly improved.
关键词： doping,perovskite solar cells,PEIE,SnO2,electron transport layer
更新于2025-09-19 17:13:59
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Influence of PEIE interlayer on detectivity of red-light sensitive organic non-fullerene photodetectors with reverse structure
摘要： In this work we analyse an influence of 80 % ethoxylated polyethyleneimine (PEIE) interlayer modifying the ITO electrode work function on the detectivity and time response of the red-light sensitive photodetectors based on donor-acceptor copolymer HFQx-T (where HFQx stands for hexafluoroquinoxaline acceptor units, and T for benzodithiophene derivative donor blocks) blended with acceptor ITIC (with indacenodithieno[3,2-b]thiophene as central donor unit and 2-(3-oxo-2,3-dihydroinden-1-ylidene) malononitrile as acceptor end groups). Modification of ITO electrode by PEIE interlayer allows to construct the photodiode with reversed structure which results in low dark current and high detectivity of the photodetector. The 3.5 nanometres thick PEIE interlayer causes strong reduction of the dark current in comparison to the dark current measured in classical photodiode structure; this allowed to obtain remarkably high detectivity, exceeding 2×1013 Jones. However, a presence of the PEIE interlayer has significantly lengthen the photodiode time response. We demonstrate that when designing the photodiodes with reversed structure, one should consider compromise between the required detectivity and the time response of the photodetector.
关键词： organic photodiode with reverse structure,ethoxylated polyethyleneimine,photodetector detectivity,photodetector time response,PEIE,organic photodetector
更新于2025-09-12 10:27:22