Multi-source cation/anion doping towards efficient carbon-based CsPbIBr2 solar cells with superior open voltage up to 1.37 V

Br-rich inorganic perovskite CsPbIBr2, has gained intense attention for photovoltaic application owing to its excellent thermal stability and appropriate band gap for the top cell of tandem solar cell. However, in most case, the open voltage (V-oc) of highly efficient CsPbIBr2 solar cell is below 1.3 V which is far from the requirement for a top cell. Herein, a novel multi-source cation/anion co-doping strategy has been used in CsPbIBr2 solar cell, which produces multiple benefits to improve the device performance. Using a multi-source co-doping strategy, carbon-based planar CsPbIBr2 solar cell achieved a respectable V-oc of 1.37 V with an efficiency of 10.78%, which is the highest V-oc reported for highly efficient CsPbIBr2 solar cell so far. This simple multi-source cation/anion doping strategy not only improves the film quality but also strengthens built-in potential, resulting in the significant enhancement of V-oc. Moreover, device with multi-source co-doping shows a much better long-term stability than that of undoped device. This work opens up a facile and efficient method to improve the V-oc and efficiency of inorganic perovskite solar cell for tandem solar cell and other optoelectronic application.