In situ simultaneous photovoltaic and structural evolution of perovskite solar cells during film formation
In situ simultaneous photovoltaic and structural evolution of perovskite solar cells during film formation
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DOI：
10.1039/c7ee03013d
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发表时间：
2018-02-01
影响因子：
32.5
通讯作者：
Lilliu, Samuele
中科院分区：
文献类型：
--
作者：
Alsari, Mejd;Bikondoa, Oier;Lilliu, Samuele
尽管存在许多结构和化学缺陷，金属卤化物钙钛矿仍表现出非常干净的半导体行为，其优异的太阳能电池性能证明了这一点。在这里，我们展示了这种清洁的半导体性能如何在金属盐和有机基前体和溶剂转化的最早阶段发挥作用，同时使用原位同步加速器 X 射线和操作电流电压测量对叉指背接触基板上制备的薄膜进行测量。一旦电极上存在足够的半导体材料，这些结构就可以用作工作太阳能电池。我们发现，在从前体相转化的第一阶段，在体电导的渗透阈值下，观察到高光电压，即使大部分材料仍然作为前体存在。这表明在钙钛矿结构形成的最早阶段，半导体能隙已经明确且没有亚能隙陷阱态。相反，短路电流持续增长，直到钙钛矿相完全形成，此时存在电荷扩散和收集的体路径。这项工作揭示了前驱体转化与器件性能之间的重要关系，并强调了钙钛矿材料卓越的缺陷容限。
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.