Ultra low-haze and high transparency thermochromic perovskite smart windows with high solar modulation ability

Abstract

Simultaneous modulation of solar radiation in response to temperature fluctuations and electricity generation through solar energy harvesting make thermochromic perovskite smart windows (TPSWs) promising candidates for smart windows. However, their application has been limited by stringent low humidity fabrication conditions and defective perovskite morphology, resulting in low solar modulation ability (ΔT_sol), high optical haze, and low power conversion efficiency (PCE). To tackle these obstacles, an antisolvent treatment method for producing high-quality TPSWs has been proposed, which also facilitated the protection of the TPSWs from moisture during ambient fabrication. The antisolvent-treated thermochromic perovskite smart windows (A-TPSW) demonstrated significantly improved optical properties, achieving a high cold-state luminous transmittance (T_lum) of 89.3 % and a new record for ΔT_sol of 31.1 % among all reported TPSWs. Additionally, this treatment reduced the optical haze of A-TPSWs from 71.71 % to 11.61 %. Moreover, it remarkably improved the perovskite morphology and achieved a 2 % PCE of A-TPSWs with a relatively low transition temperature (55 °C) and shorter transition time (3 mins). Overall, the antisolvent treatment proved an efficient method to enhance the optical and photovoltaic performance of TPSWs, while enabling low-cost device fabrication in uncontrolled humid environments. This advancement supports the broader application of smart windows in energy-efficient buildings.