Jiang Xiaoqing, Zhang Jiafeng, Liu Xiaotao, Wang Ziyuan, Guo Xin, Li Can
State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Angew Chem Int Ed Engl. 2022 Mar 14;61(12):e202115663. doi: 10.1002/anie.202115663. Epub 2022 Jan 27.
Organic ammonium salts (OASs) have been widely used to passivate perovskite defects. The passivation mechanism is usually attributed to coordination of OASs with unpaired lead or halide ions, yet ignoring their interaction with excess PbI on the perovskite film. Herein, we demonstrate that OASs not only passivate defects by themselves, but also redistribute excess aggregated PbI into a discontinuous layer, augmenting its passivation effect. Moreover, alkyl OAS is more powerful to disperse PbI than a F-containing one, leading to better passivation and device efficiency because F atoms restrict the intercalation of OAS into PbI layers. Inspired by this mechanism, exfoliated PbI nanosheets are adopted to provide better dispersity of PbI , further boosting the efficiency to 23.14 %. Our finding offers a distinctive understanding of the role of OASs in reducing perovskite defects, and a route to choosing an OAS passivator by considering substitution effects rather than by trial and error.
有机铵盐（OASs）已被广泛用于钝化钙钛矿缺陷。钝化机制通常归因于OASs与未配对的铅或卤离子的配位作用，然而却忽略了它们与钙钛矿薄膜上过量PbI的相互作用。在此，我们证明OASs不仅自身能钝化缺陷，还能将过量聚集的PbI重新分布成不连续层，增强其钝化效果。此外，烷基OAS比含氟OAS更能有效分散PbI，由于氟原子限制了OAS插入PbI层，从而带来更好的钝化效果和器件效率。受此机制启发，采用剥离的PbI纳米片可使PbI具有更好的分散性，进而将效率进一步提高至23.14%。我们的发现为理解OASs在减少钙钛矿缺陷中的作用提供了独特视角，并为通过考虑取代效应而非反复试验来选择OAS钝化剂提供了一条途径。
