Photoelectric and thermochromic properties of CsPbIBr2-based all inorganic semitransparent devices

The photovoltaic thermochromic smart window, which combines perovskite with thermochromic and photovoltaic properties, can not only control the solar transmittance at different temperatures, but also convert the absorbed light energy into usable electric energy. Herein, we designed a fluoride-doped tin oxide (FTO)/SnO2/CsPbIBr2/NiOx/indium tin oxide (ITO) semitransparent solar cell structure by using the optimized post-annealing process and obtained an average visible transmittance (AVT) of 33.2% and a power conversion efficiency of 3.89% under the optimal conditions. Meanwhile, based on the thermochromic properties of CsPbIBr2, it was found that the AVT of the device improved from 33.2% to 73.5% when CsPbIBr2 converted from the colored high-temperature phase to the transparent low-temperature phase. Besides, the transition from high-temperature phase to low-temperature phase is humidity-dominated. When the relative humidity rises from 50% to 90%, the phase transition time of perovskite decreases substantially from 1005 to 17 min. However, the excessively fast phase transition caused by high humidity will destroy the thin film morphology and crystal structure of perovskite, causing irreversible damage to CsPbIBr2 perovskite. This work is promising for the application of semitransparent photovoltaic and thermochromic smart window, which represents an attractive prospect in further reducing the energy consumption of buildings and automobiles.