Ren Jiahao, Liu Tanghao, He Bingchen, Wu Guangbao, Gu Hao, Wang Bingzhe, Li Jielei, Mao Yulin, Chen Shi, Xing Guichuan
Department of Physics and Chemistry, Faculty of Science and Technology, University of Macau, Avenida da Universidade, Taipa, Macau, 999078, China.
Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau, 999078, China.
Small. 2022 Nov;18(47):e2203536. doi: 10.1002/smll.202203536. Epub 2022 Oct 13.
The interface of perovskite solar cells (PSCs) plays a significant role in influencing their performance, yet there is still scarce research focusing on their difficult-to-expose bottom interfaces. Herein, ethylammonium bromide (EABr) is introduced into the bottom interface and its passivation effects are studied directly. First, EABr can improve substrate wettability, which is beneficial for the perovskite-film deposition. By lifting off the perovskite film spontaneously from the substrate, it is found that EABr can significantly reduce the amount of unreacted PbI at the bottom interface. These PbI crystals have been recently identified as a major defect source and degradation site for perovskite film. Meanwhile, EABr also lifts the valence band maximum at the bottom side of perovskite from -5.38 to -5.09 eV, facilitating better hole transfer. Such a improvement is also verified by the study of charge carrier dynamics. Through introducing EABr, all photovoltaic parameters of the inverted PSCs are improved, and their power conversion efficiency (PCE) increases from 20.41% to 21.06%. The study highlights the importance of direct characterization of the bottom interface for a better passivation effect.
钙钛矿太阳能电池（PSCs）的界面在影响其性能方面起着重要作用，然而，针对其难以暴露的底部界面的研究仍然很少。在此，将溴化乙铵（EABr）引入底部界面并直接研究其钝化效果。首先，EABr可以改善基底润湿性，这有利于钙钛矿薄膜的沉积。通过从基底上自发剥离钙钛矿薄膜，发现EABr可以显著减少底部界面处未反应的PbI的量。这些PbI晶体最近被确定为钙钛矿薄膜的主要缺陷源和降解位点。同时，EABr还将钙钛矿底部的价带最大值从-5.38 eV提升至-5.09 eV，促进了更好的空穴传输。电荷载流子动力学研究也证实了这种改善。通过引入EABr，倒置PSC的所有光伏参数均得到改善，其功率转换效率（PCE）从20.41%提高到21.06%。该研究强调了直接表征底部界面以获得更好钝化效果的重要性。
