All-Inorganic CsPbI2Br Perovskite Solar Cell with Open-Circuit Voltage over 1.3 V by Balancing Electron and Hole Transport

The energy loss of all-inorganic metal halide perovskite solar cells is large, which reduces the open-circuit voltage and photoelectron conversion efficiency of the device. Herein, it is found that the cathode electron transfer speed is much lower than the anode hole transfer speed in CsPbI2Br perovskite solar cell with fluorine-doped tin oxide (FTO) glass/SnO2/CsPbI2Br/carbon structure, which induces charge accumulation at the cathode and energy loss of the device accordingly. By introducing a new conductive polymer additive polyaniline (PANI) to the CsPbI2Br film, the electron transfer speed at the cathode is enhanced, resulting in balanced charge transfer at both electrodes and reduced energy loss of the device. Ultraviolet photoelectron spectroscopy measurement reveals that the PANI pushes the conduction band minimum of CsPbI2Br upward, leading to stronger driving force for electron extraction. Therefore, the nonradiative recombination at the SnO2/CsPbI2Br interface is greatly suppressed. In addition, PANI can also effectively passivate defects and promote the crystal quality of CsPbI2Br, leading to reduced nonradiative recombination in perovskite materials. Accordingly, the optimized all-inorganic CsPbI2Br solar cell delivers a high V-oc of 1.33 V and power conversion efficiency (PCE) of 13.52%.