The demand for lightweight, flexible, and high-performance portable power sources urgently requires high-efficiency and stable flexible solar cells. In the case of perovskite solar cells (PSCs), most of the common electron transport layer (ETL) needs to be annealed for improving the optoelectronic properties, while conventional flexible substrates could barely stand the high temperature. Herein, a vacuum-assisted annealing SnO₂ ETL at low temperature (100 °C) is utilized in flexible PSCs and achieved high efficiency of 20.14%. Meanwhile, the open-circuit voltage (V_oc) increases from 1.07 V to 1.14 V. The flexible PSCs also show robust bending stability with 86.8% of the initial efficiency is retained after 1000 bending cycles at a bending radius of 5 mm. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements show that the density of oxygen vacancies, the surface roughness of the SnO₂ layer, and film hydrophobicity are significantly increased, respectively. These improvements could be due to the oxygen-deficient environment in a vacuum chamber, and the rapid evaporation of solvents. The proposed vacuum-assisted low-temperature annealing method not only improves the efficiency of flexible PSCs but is also compatible and promising in the large-scale commercialization of flexible PSCs.

对轻便、灵活、高性能的便携式电源的需求迫切需要高效、稳定的柔性太阳能电池。在钙钛矿太阳能电池（PSC）的情况下，大多数常见的电子传输层（ETL）需要退火以提高光电性能，而传统的柔性基板几乎无法承受高温。在此，低温（100°C）真空辅助退火 SnO ₂ ETL 用于柔性 PSC，并实现了 20.14% 的高效率。同时，开路电压（V _OC) 从 1.07 V 增加到 1.14 V。柔性 PSC 还表现出强大的弯曲稳定性，在弯曲半径为 5 mm 的情况下，在 1000 次弯曲循环后仍保持 86.8% 的初始效率。X 射线光电子能谱 (XPS)、原子力显微镜 (AFM) 和接触角测量表明，氧空位密度、SnO ₂层的表面粗糙度和薄膜疏水性分别显着增加。这些改进可能是由于真空室中的缺氧环境和溶剂的快速蒸发。所提出的真空辅助低温退火方法不仅提高了柔性 PSC 的效率，而且在柔性 PSC 的大规模商业化中具有兼容性和前景。