Monovalent Copper Cation Doping Enables High-Performance CsPbIBr(2)-Based All-Inorganic Perovskite Solar Cells

Organic–inorganic perovskite solar cells (PSCs) have delivered the highest power conversion efficiency (PCE) of 25.7% currently, but they are unfortunately limited by several key issues, such as inferior humid and thermal stability, significantly retarding their widespread application. To tackle the instability issue, all-inorganic PSCs have attracted increasing interest due to superior structural, humid and high-temperature stability to their organic–inorganic counterparts. Nevertheless, all-inorganic PSCs with typical CsPbIBr(2) perovskite as light absorbers suffer from much inferior PCEs to those of organic–inorganic PSCs. Functional doping is regarded as a simple and useful strategy to improve the PCEs of CsPbIBr(2)-based all-inorganic PSCs. Herein, we report a monovalent copper cation (Cu(+))-doping strategy to boost the performance of CsPbIBr(2)-based PSCs by increasing the grain sizes and improving the CsPbIBr(2) film quality, reducing the defect density, inhibiting the carrier recombination and constructing proper energy level alignment. Consequently, the device with optimized Cu(+)-doping concentration generates a much better PCE of 9.11% than the pristine cell (7.24%). Moreover, the Cu(+) doping also remarkably enhances the humid and thermal durability of CsPbIBr(2)-based PSCs with suppressed hysteresis. The current study provides a simple and useful strategy to enhance the PCE and the durability of CsPbIBr(2)-based PSCs, which can promote the practical application of perovskite photovoltaics.