A perovskite solar cell-powered smart window with high initial transparency for tri-band solar spectrum management

Intelligent thermal management through self-adaptive optical modulation of smart windows is a key technology for green buildings. Integrating solar cells into electrochromic smart windows can further enhance energy conservation, yet their application is still hindered by the limited initial transmittance. Here, we report a self-powered electrochromic smart window by integrating an electrochromic module into a fully transparent perovskite solar cell with a vertically stacked configuration. The device exhibits an average visible light (VIS) transmittance of ~ 86.8% and can convert ultraviolet (UV) light into electrical energy with VOC of 0.83 V and JSC of 0.98 mA cm−2 to drive the electrochromic function, achieving an outstanding VIS and near-infrared (NIR) optical modulation (43% at 640 nm and 57% at 1100 nm). Notably, the device autonomously modulates its transmittance in response to varying solar irradiance, enabling adaptive control of indoor luminance and temperature. The simulation results evaluated in six representative cities across distinct climate zones demonstrate that the device can offer annual energy savings of 11.9%-39.3% over commercial glass.