Institute of Physical Chemistry, Polish Academy of Sciences , Kasprzaka 44/52, 01-224 Warsaw, Poland.
J Am Chem Soc. 2017 Oct 11;139(40):14173-14180. doi: 10.1021/jacs.7b07223. Epub 2017 Sep 27.
Hybrid (organic-inorganic) multication lead halide perovskites hold promise for a new generation of easily processable solar cells. Best performing compositions to date are multiple-cation solid alloys of formamidinium (FA), methylammonium (MA), cesium, and rubidium lead halides which provide power conversion efficiencies up to around 22%. Here, we elucidate the atomic-level nature of Cs and Rb incorporation into the perovskite lattice of FA-based materials. We use Cs, Rb, K, C, and N solid-state MAS NMR to probe microscopic composition of Cs-, Rb-, K-, MA-, and FA-containing phases in double-, triple-, and quadruple-cation lead halides in bulk and in a thin film. Contrary to previous reports, we have found no proof of Rb or K incorporation into the 3D perovskite lattice in these systems. We also show that the structure of bulk mechanochemical perovskites bears close resemblance to that of thin films, making them a good benchmark for structural studies. These findings provide fundamental understanding of previously reported excellent photovoltaic parameters in these systems and their superior stability.
混合（有机-无机）多阳离子卤化铅钙钛矿有望成为新一代易于处理的太阳能电池。迄今为止表现最好的成分是甲脒（FA）、甲基铵（MA）、铯和铷铅卤化物的多阳离子固溶体合金，其提供的功率转换效率高达 22%左右。在这里，我们阐明了 Cs 和 Rb 掺入 FA 基材料钙钛矿晶格的原子水平性质。我们使用 Cs、Rb、K、C 和 N 固态 MAS NMR 来探测双、三、四阳离子卤化铅中 Cs、Rb、K、MA 和 FA 所含相的微观组成块状和薄膜。与之前的报告相反，我们在这些系统中没有发现 Rb 或 K 掺入 3D 钙钛矿晶格的证据。我们还表明，机械化学钙钛矿的体相结构与薄膜非常相似，使其成为结构研究的良好基准。这些发现为这些系统中先前报道的优异光伏参数及其优异的稳定性提供了基本的理解。
