Solid-state µ-MAS and thin-film NMR spectroscopy on hybrid organic/inorganic perovskite photovoltaic materials

混合有机/无机卤化铅钙钛矿（APbX 3）在过去十年中引起了极大的兴趣，因为它们可能用作传统硅太阳能电池的替代品，具有目前高达23%的优异功率转换效率。由于柔性结构，可获得包括混合阳离子和/或混合卤化物体系的宽带宽的化学组合物。此外，一系列不同的合成策略和所得钙钛矿的处理是可能的，除了化学组成影响例如钙钛矿材料的形态、粒度和晶体缺陷之外。这些不同水平的结构变化通常会对所得薄膜钙钛矿的光电性质产生相互关联的影响，所述薄膜钙钛矿是用于太阳能电池应用的材料几何形状。与巨大的参数空间相比，系统的研究是罕见的，并且基本上缺少太阳能电池的原位工作条件，即照射。然而，在原子分辨率的全面研究是必不可少的，以获得结构-性能关系，以指导未来的合成策略和最佳的化学组成，以实现高效率的卤化铅钙钛矿。因此，该研究建议致力于关闭这一差距，为一套混合的混合有机/无机卤化铅钙钛矿薄膜的几何形状。为此，我们选择了NMR晶体学方法，因为它提供了补充信息的本地环境在原子水平上，除了长程有序，从而代表了系统的结构研究的最佳方法。基于微线圈设计的新型薄膜MAS NMR探头的开发和实现将允许直接测量薄膜的几何形状。此外，光源将安装在体相和薄膜MAS NMR探针中，以允许在照射时原位监测多种钙钛矿组合物和形态的结构行为。我们期待着一系列高性能光伏钙钛矿材料的关键问题，点缺陷，阳离子或卤化物有序/无序，以及光照射后的结构响应对光电性能的影响将得到回答。整体样品和薄膜几何形状的结果的比较将提供洞察力的影响，合成，从而结晶conditions.Overall，实现结构的洞察力关于高性能的钙钛矿材料在实际设备的工作条件下，最终将指向重要的结构-性能关系，以指导未来定制的钙钛矿材料相对于其在太阳能电池设备中的应用。

Hybrid organic/inorganic lead halide perovskites (APbX3) have attracted great interest in the last decade due to their possible application as an alternative to conventional silicon solar cells, with excellent power conversion efficiencies of currently up to 23 %. Due to the flexible structure a wide bandwidth of chemical compositions including mixed cation and/or mixed halide systems are accessible. Furthermore, a series of different synthesis strategies and treatment of the resulting perovskites are possible, that besides chemical compositions impact on e.g. the morphology, particle size and crystallographic defects of the perovskite materials. These structural changes at varying levels often cause interlinked effects on the optoelectronic properties of the resulting thin film perovskites, the materials geometry that is used in solar cell applications. Systematic studies are rare compared to the enormous parameter space, and are essentially missing for in situ working conditions of solar cells, i.e. upon illumination. However, comprehensive studies at atomic resolution are essential to derive structure-property relations in order to guide future synthesis strategies and optimal chemical compositions for high efficiencies of lead halide perovskites. The research proposal, therefore, is dedicated to the closure of this gap for a suit of mixed hybrid organic/inorganic lead halide perovskites in thin film geometries. For this purpose we choose the NMR crystallographic approach as it provides complementary information about the local environment at atomic level in addition to long-range order, and thus represents the optimal methodology for systematic structural studies. The development and implementation of a novel thin film MAS NMR probehead based on microcoil designs will allow for direct measurements of thin film geometries. Furthermore, light sources will be installed in both, bulk and thin film MAS NMR probes, in order to allow for monitoring the structural behaviour of multiple perovskite compositions and morphologies in situ upon illumination. We expect that the key issues, how point defects, cation or halide order/disorder, as well as the structural response upon light irradiation impact on the optoelectronic properties will be answered for a suit of high-performance photovoltaic perovskite materials. The comparison of the results for both bulk samples and thin film geometries will provide insights in the influence of syntheses and thus crystallization conditions.Overall, the achieved structural insights about high-performance perovskite materials under actual device working conditions will eventually point to important structure-property relations to guide future tailoring of perovskite materials with respect to their application in solar cell devices.