Low temperature fabrication for high-performance semitransparent CsPbI2Br perovskite solar cells

All-inorganic CsPbI₂Br perovskite with suitable bandgap and excellent thermal stability has been reported as the most promising candidate for efficient perovskite solar cells (PSCs). However, the high annealing temperature (> 250 °C) and poor stability of α-CsPbI₂Br greatly limit the future application in photovoltaic field. Herein, a facile method is reported to prepare α-CsPbI₂Br perovskite film with high stability at low temperature (70 °C) by incorporating a small amount of γ-aminobutyric acid (GABA) in the precursor solutions. The devices exhibit reproducible photovoltaic performance with a champion efficiency up to 15.16%, along with the excellent stability, maintaining more than 80% of its initial efficiency after stored in ambient condition for 600 h without any encapsulation. Most importantly, the method enables fabrication of semitransparent CsPbI₂Br PSCs with a PCE of 6.76%, as well as an average visible transparency (AVT) of 25.38%. To the best of our knowledge, this is the first attempt to apply CsPbI₂Br to the semitransparent solar cells.