Minute‐Level Room‐Temperature Switching and Long Cycle Stability of Thermochromic Inorganic Perovskite Smart Windows

Abstract Perovskite smart windows (PSWs) are widely investigated owing to excellent thermochromic properties, while restricted by poor transition performance and cycle stability. Herein, dimethyl sulfoxide vapor is utilized as an induction reagent for rapid reversible switching at room temperature between the colored and bleached phases. To obtain PSWs with different optical properties and transition performance, red CsPbIBr 2 , yellow Rb 0.5 Cs 0.5 PbIBr 2 and brown CsSn 0.1 Pb 0.9 IBr 2 are prepared through alloying. The perovskites can exhibit reversible switching at 27.4–34.3 °C within 1.9–5.1 min. Even after 100 cycles, they exhibit remarkable stability of luminous transmittance (retention ≥97.4%) and transition time (retention ≥97.6%). Experimental characterization proves that the reversible switching occurs between colored three‐dimension perovskite phase and bleached zero‐dimension perovskite phase. In the field test (air temperature = 21.6–26.5 °C), model houses with PSWs exhibit a maximum indoor temperature drop of 4.2 °C. Furthermore, they exhibit considerable temperature modulation ability up to 7.9 °C under a solar simulator (temperature of the control model house = 60 °C). The decrease in the luminous transmittance of the PSWs after 20 days is 2.9%, indicating excellent long‐term stability. This study offers PSWs with prominent transition performance and long cycle stability.