德国柏林亥姆霍兹研究所 Jorge Pascual团队报道了卤化锡钙钛矿中的氟化物化学。相关研究成果于2021年7月7日发表在国际顶尖学术期刊《德国应用化学》。

在钙钛矿型太阳能电池中，锡是替代有毒铅的领跑者。然而，锡会受到Sn（II）到Sn（IV）的有害氧化。大多数报道的方法是在钙钛矿前驱体溶液中使用SnF2来阻止Sn（IV）的形成。然而，这种添加剂的作用机理仍存在争议。

为了进一步阐明这一点，研究人员利用辅助分析工具研究了锡卤化物钙钛矿中的氟化物化学。前驱体溶液的NMR揭示了氟阴离子对Sn（IV）比Sn（II）的具有更强的优先亲和性，选择性地将其络合为SnF4。硬X射线光电子能谱表明SnF4比SnI4更容易被钙钛矿结构所包裹，从而阻止了Sn（IV）在薄膜中的包裹。

最后，小角X射线散射揭示了氟对前驱体分散体胶体化学的强烈影响，即直接影响钙钛矿的结晶。结合这些分析工具，研究人员提供了氟化物工作机制的完整图片。

附：英文原文

Title: Fluoride Chemistry in Tin Halide Perovskites

Author: Jorge Pascual, Marion Flatken, Roberto F, Guixiang Li, Silver-Hamill Turren-Cruz, Mahmoud H. Aldamasy, Claudia Hartmann, Meng Li, Diego Di Girolamo, Giuseppe Nasti, Elif Hü, Regan G. Wilks, Andr, Marcus B, Armin Hoell, Antonio Abate

Issue&Volume: 2021-07-07

Abstract: Tin is the frontrunner for substituting toxic lead in perovskite solar cells. However, tin suffers the detrimental oxidation of Sn(II) to Sn(IV). Most of reported strategies employ SnF  2  in the perovskite precursor solution to prevent Sn(IV) formation. Nevertheless, the working mechanism of this additive remains debated. To further elucidate it, we investigate the fluoride chemistry in tin halide perovskites by complementary analytical tools. NMR of the precursor solution discloses a strong preferential affinity of fluoride anions for Sn(IV) over Sn(II), selectively complexing it as SnF  4  . Hard X-ray photoelectron spectroscopy on films shows the lower tendency of SnF  4  than SnI  4  to get included in the perovskite structure, hence preventing the inclusion of Sn(IV) in the film. Finally, small-angle X-ray scattering reveals the strong influence of fluoride on the colloidal chemistry of precursor dispersions, directly affecting perovskite crystallization. Combining these analytical tools, we provide a complete picture of fluoride's working mechanism.

DOI: 10.1002/anie.202107599

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202107599