Interfacial Oxygen Vacancies as a Potential Cause of Hysteresis in Perovskite Solar Cells

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• 作者：Fan Zhang ; Wei Ma ; Haizhong Guo ; Yicheng Zhao ; Xinyan Shan ; Kuijuan Jin ; He Tian ; Qing Zhao ; Dapeng Yu ; Xinghua Lu ; Gang Lu ; Sheng Meng
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：February 9, 2016
• 年：2016
• 卷：28
• 期：3
• 页码：802-812
• 全文大小：581K
• ISSN：1520-5002

文摘

Organometal halide perovskite solar cells (PSCs) have emerged as one of the most promising photovoltaic technologies with efficiencies exceeding 20.3%. However, device stability problems including hysteresis in current–voltage scans must be resolved before the commercialization of PSCs. Transient absorption measurements and first-principles calculations indicate that the migration of oxygen vacancies in the TiO₂ electrode under electric field during voltage scans contributes to the anomalous hysteresis in PSCs. The accumulation of oxygen vacancies at the electrode/perovskite interface slows down charge extraction while significantly speeding up charge recombination at the interface. Moreover, nonadiabatic molecular dynamics simulations reveal that the charge recombination rates at the interface depend sensitively (with 1 order of magnitude difference) on the locations of oxygen vacancies. By intentionally reducing oxygen vacancies in the TiO₂ electrode, we substantially suppress unfavorable hysteresis in the PSC devices. This work establishes a firm link between microscopic interfacial structure and macroscopic device performance of PSCs, providing important clues for future device design and optimization.