Fig. 1: Working principle of the mask-inspired thermochromic perovskite window (MTPW) and its fabrication process.

a Schematic of the trilayer structure and working principle of an antivirus medical mask. b Schematic of the trilayer structure and working principle of the MTPW for repelling water and excess water vapor. c Photographs of the MTPW in the cold and hot states. d Complex refractive index of T-Perovskite in the cold and hot states as well as the fabricated PHPS in this study. e Solution-based fabrication process of the MTPW. Firstly, a mixture of methylammonium iodide (MAI) and lead chloride (PbCl₂) in a molar ratio of 6.5:1 is prepared. This mixture is then spin-coated onto a glass substrate, followed by an annealing process. Next, perhydropolysilazane (PHPS) is spin-coated on top of the thermochromic perovskite layer and subsequently annealed. Finally, a layer of silicon dioxide (SiO₂) nanoparticles is spray-coated onto the PHPS layer. Source data are provided as a Source Data file.