Metal-halide perovskites show remarkably clean semiconductor behaviour, as evidenced by their excellent solar cell performance, in spite of the presence of many structural and chemical defects. Here, we show how this clean semiconductor performance sets in during the earliest phase of conversion from the metal salts and organic-based precursors and solvent, using simultaneous in situ synchrotron X-ray and in operando current–voltage measurements on films prepared on interdigitated back-contact substrates. These structures function as working solar cells as soon as sufficient semiconductor material is present across the electrodes. We find that at the first stages of conversion from the precursor phase, at the percolation threshold for bulk conductance, high photovoltages are observed, even though the bulk of the material is still present as precursors. This indicates that at the earliest stages of perovskite structure formation, the semiconductor gap is already well-defined and free of sub-gap trap states. The short circuit current, in contrast, continues to grow until the perovskite phase is fully formed, when there are bulk pathways for charge diffusion and collection. This work reveals important relationships between the precursors conversion and device performance and highlights the remarkable defect tolerance of perovskite materials.

中文翻译：

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膜形成过程中钙钛矿型太阳能电池的原位同时光伏和结构演化†

尽管存在许多结构和化学缺陷，但金属卤化物钙钛矿却显示出非常干净的半导体性能，这由其出色的太阳能电池性能证明。在这里，我们展示了同时使用原位同步加速器X射线和在操作中从金属盐和有机基前体和溶剂转化的最早阶段，这种清洁的半导体性能是如何产生的。在指状背接触基板上制备的薄膜上的电流-电压测量。一旦在电极之间存在足够的半导体材料，这些结构就可以用作工作的太阳能电池。我们发现，在从前驱物相转化的第一阶段，在体积电导的渗透阈值处，尽管大部分材料仍以前驱物形式存在，但仍观察到高光电压。这表明在钙钛矿结构形成的最早阶段，半导体间隙已经被很好地定义并且没有亚间隙陷阱态。相反，当存在用于电荷扩散和收集的大量途径时，短路电流继续增长，直到钙钛矿相完全形成为止。