Smart photovoltaic windows represent a promising green technology featuring tunable transparency and electrical power generation under external stimuli to control the light transmission and manage the solar energy. Here, we demonstrate a thermochromic solar cell for smart photovoltaic window applications utilizing the structural phase transitions in inorganic halide perovskite caesium lead iodide/bromide. The solar cells undergo thermally-driven, moisture-mediated reversible transitions between a transparent non-perovskite phase (81.7% visible transparency) with low power output and a deeply coloured perovskite phase (35.4% visible transparency) with high power output. The inorganic perovskites exhibit tunable colours and transparencies, a peak device efficiency above 7%, and a phase transition temperature as low as 105 °C. We demonstrate excellent device stability over repeated phase transition cycles without colour fade or performance degradation. The photovoltaic windows showing both photoactivity and thermochromic features represent key stepping-stones for integration with buildings, automobiles, information displays, and potentially many other technologies.

智能光伏窗代表了一种很有前途的绿色技术，具有可调节的透明度和在外部刺激下发电以控制光传输和管理太阳能。在这里，我们展示了一种用于智能光伏窗应用的热致变色太阳能电池，该电池利用无机卤化物钙钛矿铯碘化铅/溴化铅中的结构相变。太阳能电池在具有低功率输出的透明非钙钛矿相（81.7% 可见透明度）和具有高功率输出的深色钙钛矿相（35.4% 可见透明度）之间经历热驱动、水分介导的可逆转变。无机钙钛矿具有可调节的颜色和透明度，峰值器件效率超过 7%，相变温度低至 105 °C。我们在重复的相变循环中展示了出色的器件稳定性，而不会褪色或性能下降。显示光活性和热致变色特征的光伏窗代表了与建筑物、汽车、信息显示器和潜在的许多其他技术集成的关键踏脚石。