Scalable Photochromic Film for Solar Heat and Daylight Management.

The adaptive control of sunlight through photochromic smart windows could have a huge impact on the energy efficiency and daylight comfort in buildings. However, the fabrication of inorganic nanoparticle and polymer composite photochromic films with a high contrast ratio and high transparency/low haze remains a challenge. Here, we present a solution method for the in-situ growth of coper doped tungsten trioxide nanoparticles in polymethyl methacrylate, which allows a low-cost preparation of photochromic films with a high transparency (T lum = 91%) and scalability (30×350 cm 2 ). High modulation of visible light (ΔT lum = 73%) and solar heat (ΔT sol = 73%, ΔSHGC = 0.5) of the film improve the indoor daylight comfort and energy efficiency. Simulation results show that low-e windows with the photochromic film applied can greatly enhance the energy efficiency, increase the time of "comfortable" daylight illuminance level and imperceptible glare. This photochromic film presents an attractive strategy for achieving more energy-efficient buildings and carbon neutrality to combat global climate change. This article is protected by copyright. All rights reserved.