Improving inorganic perovskite photovoltaic performance via organic cation addition for efficient solar energy utilization

Organic cations help in executing better crystal growth of halide perovskites. Herein, we have realized improved all-inorganic cesium lead halide perovskite film quality with reduced pinholes and high crystallinity in phenylethylammonium (PEA+) assisted perovskite. Additionally, PEA+ cation acts as an additive to control intermediate perovskite phase and executes pure phase perovskite crystal growth as compared to MA+ and FA+ cations assisted perovskite films. X-ray photoelectron and UV–vis spectroscopy results revealed that adding PEA+ in the perovskite helps in almost uniform distribution of Br− ion after post-annealing process. Furthermore, depth profiling analysis reveals that PEA+ in the intermediate phase perovskite interacts more with the ZnO layer beneath perovskite, which helps in the fabrication of compact film. PEA+ sublimates after post-annealing treatment of 300 °C, as no evidence of PEA+ existence was found in characterizations for post-annealed perovskite films. This brings multiple benefits to inorganic mixed halide perovskite film formation. The best performing perovskite solar cell (PSC) exhibits a high conversion efficiency of 14.75% as well as enhanced stability of maintaining almost 83% of its initial efficiency for 400 h. Electrochemical impedance spectroscopy and space-charge-limited current results suggests reduced recombination loss and defect densities in PEA+ assisted PSC.