中科院大连化学物理研究所郭鑫团队报道了有机铵离子在减少钙钛矿薄膜表面缺陷中的深刻见解。相关研究成果于2022年1月5日发表于国际顶尖学术期刊《德国应用化学》。

有机铵盐（OASs）被广泛用于钝化钙钛矿缺陷。钝化机理通常归因于OASs与未配对的铅或卤化物离子的配位，但忽略了它们与钙钛矿薄膜上过量PbI₂的相互作用。

该文中，研究人员证明OASs不仅自身钝化缺陷，而且还将过量聚集的PbI 2重新分布到不连续层中，增强其钝化效果。此外，烷基OAS比含F的OAS更能分散PbI₂，由于F原子限制OAS插层到Pbi₂层中，因此导致更好的钝化和器件效率。受该机制启发，研究人员采用剥离的PbI₂纳米片来提供更好的PbI₂分散性，进一步将效率提高到23.14%。

该发现为OASs在减少钙钛矿缺陷方面的作用提供了独特的理解，并为通过考虑替代效应而非反复试验来选择OAS钝化剂提供了线索。

附：英文原文

Title: Deeper Insight into the Role of Organic Ammonium Cations in Reducing Surface Defects of the Perovskite Film

Author: Xiaoqing Jiang, Jiafeng Zhang, Xiaotao Liu, Ziyuan Wang, Xin Guo, Can Li

Issue&Volume: 2022-01-05

Abstract: 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  2  on the perovskite film. Herein, we demonstrate that OASs not only passivate defects by themselves, but also redistribute excess aggregated PbI  2  into a discontinuous layer, augmenting its passivation effect. Moreover, alkyl OAS is more powerful to disperse PbI  2  than F-containing one, leading to better passivation and device efficiency because F atoms restrict the intercalation of OAS into PbI  2  layers. Inspired by this mechanism, exfoliated PbI  2  nanosheets are adopted to provide better dispersity of PbI  2  , further boosting the efficiency to 23.14%. Our finding offers a distinctive understanding on the role of OASs in reducing perovskite defects, and a clue to choose an OAS passivator by considering substitution effect other than by trial and error.

DOI: 10.1002/anie.202115663

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202115663