Solution-processed metal halide perovskite semiconductors, such as CH3NH3PbI3, have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is halide vacancies within the perovskite crystals, or the presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which could evolve during crystallization. Herein, we show that the addition of hypophosphorous acid (HPA) in the precursor solution can significantly improve the film quality, both electronically and topologically, and enhance the photoluminescence intensity, which leads to more efficient and reproducible photovoltaic devices. We demonstrate that the HPA can reduce the oxidized I2 back into I(-), and our results indicate that this facilitates an improved stoichiometry in the perovskite crystal and a reduced density of metallic lead.

中文翻译：

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具有次磷酸的钙钛矿薄膜的光电性能增强，用于平面异质结太阳能电池。

固溶处理的金属卤化物钙钛矿半导体，例如CH3NH3PbI3，尽管具有不可忽略的缺陷态密度，但在太阳能电池中仍表现出卓越的性能。钙钛矿晶体中的卤化物空位或金属铅的存在可能是由于结晶过程中可能发生的I / Pb化学计量失衡而产生的。本文中，我们表明在前体溶液中添加次磷酸（HPA）可以显着改善电子和拓扑结构的薄膜质量，并增强光致发光强度，从而导致更高效和可重现的光伏器件。我们证明了HPA可以将氧化的I2还原回I（-），