Perovskite photovoltachromic cells for building integration

Photovoltachromic devices combine photovoltaic and electrochromic behaviours to enable adjustable transparency glazing, where the photovoltaic component supplies the power to drive the coloration. Such stand-alone, self-powered devices are of commercial interest for integration into windows and surfaces of buildings and vehicles. Here, we report for the first time a perovskite-based photovoltachromic device with self-adaptive transparency. This multifunctional device is capable of producing electrical power by solar energy conversion as well as undergoing a chromic transition from neutral-color semi-transparent to dark blue-tinted when irradiated with solar light, without any additional external bias. The combination of semi-transparent perovskite photovoltaic and solid-state electrochromic cells enables fully solid-state photovoltachromic devices with 26% (or 16%) average visible transmittance and 3.7% (or 5.5%) maximum light power conversion efficiency. Upon activating the self-tinting, the average visible transmittance drops to 8.4% (or 5.5%). These results represent a significant step towards the commercialization of photovoltachromic building envelopes.