Formamidinium lead iodide (FAPbI₃) perovskite is a front-runner material for efficient perovskite solar cells (PSCs) due to its high light-absorption coefficient, narrow band gap, and superior photostability and thermostability. High-quality FAPbI₃ perovskite formation typically requires an >160°C annealing process to induce phase transition from the photoinactive yellow phase (δ-FAPbI₃) to the photoactive black phase (α-FAPbI₃). However, this high-temperature annealing can induce defects in the films and hinders application in flexible solar cells. Here, we report a facile method to fabricate high-quality α-FAPbI₃ perovskite films at room temperature, without thermal annealing or vacuum-assisted processes. Combined computational and experimental results reveal the crystallization mechanism of α-FAPbI₃ formation at room temperature. We demonstrate PSCs with a power-conversion efficiency of 19.09%, which is the highest efficiency for room temperature PSCs to the best of our knowledge. This study may offer a cost-effective way to fabricate highly efficient PSCs at room temperature.

甲酰碘化碘化铅（FAPbI ₃）钙钛矿是高效钙钛矿太阳能电池（PSC）的领先材料，因为它具有高的光吸收系数，窄的带隙以及出色的光稳定性和热稳定性。高质量FAPbI ₃钙钛矿形成通常需要> 160℃退火处理以从光活性的黄色相（δ-FAPbI诱导相转变₃），以在光活性黑相（α-FAPbI ₃）。然而，这种高温退火会在膜中引起缺陷并妨碍在柔性太阳能电池中的应用。在这里，我们报告一个浅显的方法来制作高质量的α-FAPbI ₃钙钛矿薄膜在室温下，无需热退火或真空辅助工艺。合并的计算和实验结果表明α-FAPbI结晶机构₃形成在室温下。我们展示了功率转换效率为19.09％的PSC，据我们所知，这是室温PSC的最高效率。这项研究可能提供一种在室温下制造高效PSC的经济有效的方法。