Zhou Wencai, Zhou Rongkun, Chen Xiaoqing, Zhou Zixiao, He Yongcai, Qian Cheng, Yan Hui, Zheng Zilong, Zhang Yongzhe, Yan He
College of Materials Science and Engineering, Faculty of Information Technology, Beijing University of Technology, Beijing, 100124, P. R. China.
School of Mathematics, Southeast University, Nanjing, Jiangsu, 211189, P. R. China.
Small. 2024 Nov;20(46):e2405201. doi: 10.1002/smll.202405201. Epub 2024 Aug 7.
In organic-inorganic hybrid perovskite solar cells (PSCs), hydrogen defects introduce deep-level trap states, significantly influencing non-radiative recombination processes. Those defects are primarily observed in MA-PSCs rather than FA-PSCs. As a result, MA-PSCs demonstrated a lower efficiency of 23.6% compared to 26.1% of FA-PSCs. In this work, both hydrogen vacancy (V ) and hydrogen interstitial (H ) defects in MAPbI bulk and on surfaces, respectively are investigated. i) Bulk V defects have dramatic impact on non-radiative recombination, with lifetime varying from 67 to 8 ns, depending on whether deprotonated MA are ion-bonded or not. ii) Surface H-defects exhibited an inherent self-healing mechanism through a chemical bond between MA and Pb, indicating a self-passivation effect. iii) Both V and H defects can be mitigated by alkali cation passivation; while large cations are preferable for V passivation, given strong binding energy of cation/perovskite, as well as, weak band edge non-adiabatic couplings; and small cations are suited for H passivation, considering the steric hindrance effect. The dual passivation strategy addressed diverse experimental outcomes, particularly in enhancing performance associated with cation selections. The dynamic connection between hydrogen defects and non-radiative recombination is elucidated, providing insights into hydrogen defect passivation essential for high-performance PSCs fabrication.
在有机-无机杂化钙钛矿太阳能电池（PSC）中，氢缺陷会引入深能级陷阱态，对非辐射复合过程产生显著影响。这些缺陷主要在甲基铵基钙钛矿太阳能电池（MA-PSC）中观察到，而非甲脒基钙钛矿太阳能电池（FA-PSC）。因此，MA-PSC的效率为23.6%，低于FA-PSC的26.1%。在这项工作中，分别研究了MAPbI体相和表面的氢空位（V ）和氢间隙（H ）缺陷。i）体相V 缺陷对非辐射复合有显著影响，其寿命根据去质子化的MA是否离子键合而在67至8纳秒之间变化。ii）表面H缺陷通过MA和Pb之间的化学键表现出固有的自愈机制，表明存在自钝化效应。iii）V 和H 缺陷都可以通过碱金属阳离子钝化来减轻；考虑到阳离子/钙钛矿的强结合能以及弱带边非绝热耦合，大阳离子更适合V 钝化；考虑到空间位阻效应，小阳离子适合H 钝化。这种双重钝化策略解决了各种实验结果，特别是在提高与阳离子选择相关的性能方面。阐明了氢缺陷与非辐射复合之间的动态联系，为高性能PSC制造中必不可少的氢缺陷钝化提供了见解。
