Sunflower-Inspired Zero-Energy-Consumption Thermal Switching for Dual-Mode Photochromic Smart Window

photochromic film and the lower layer of a polyurethane two-way shape memory polymer. In hot environments, an approximately 4.86 °C lower temperature is realized between a prototype house equipped with this device (with a maximum indoor temperature of 47.34 °C) compared with a house without this device (52.20 °C), which confirms the film's solar heat rejection effect. In cold conditions, the device curls to allow sunlight entry, maintaining a comfortable indoor environment. It exhibits superior recycling performance (over 200 cycles). Its exceptional thermal management capabilities and automatic switching enable optimal temperature control by selecting the appropriate mode. This zero-energy thermal management device contributes to achieving low-carbon and environmentally friendly objectives.