Dual-functional metal (IIB) diethyldithocarbamate salts passivation enabled high-efficiency and stable carbon-based CsPbIBr2 all-inorganic perovskite solar cells

Solution-prepared perovskite films are accompanied by high defect density. Defects gathered on the surface or grain boundaries of the perovskite accelerate the degradation of the perovskite and affect the photovoltaic performance and long-term stability of the device, which is one of the bottlenecks to curb the further development of perovskite solar cells (PSCs). In this work, a simple and effective surface passivation method is designed by choosing metal (IIB) diethyldithiocarbamate salts [M(DDTC)(2), M = Pb2+, Cd2+ and Zn2+]. The DDTC has excellent complexing ability with metal ions and chelate bidentately with unpaired Pb2+ ions on the surface of perovskite. IIB metal ions have a small ion radius and could easily diffuse into the perovskite to occupy Pb vacancies. The synergistic effect of anions and cations effectively reduces the defect concentration and non radiative recombination in the CsPbIBr2 all-inorganic perovskite, thereby obtaining carbon-based CsPbIBr2 all inorganic PSCs with high efficiency and high stability. Ultimately, champion efficiency of the Cd(DDTC)(2) and Zn(DDTC)(2)-treated CsPbIBr2 PSCs yield 9.59% and 10.21%, respectively, obviously higher than that of the pristine one (8.74%).