Attenuating the defect activities with a rubidium additive for efficient and stable Sn-based halide perovskite solar cells

The oxidative instability of tin-based halide perovskites (Sn-HaP) is a culprit for inferior device performance and applications in other optoelectronic devices. Here, we have investigated the impacts of a Rb additive on the FASnI(3) based device characteristics. It is observed that the RbCl additive facilitates uniform morphology with better crystal quality and suppression of oxidation of Sn2+. This results in an enhancement in the device efficiency of 3.12% for pure Sn-HaP to 5.89% for the RbCl additive with high reproducibility and superior stability. It also benefited from a higher diffusion potential and mitigation of defect activities with the RbCl additive in Sn-HaPSCs. These results corroborate that the incorporation of Rb in the FASnI(3) structure plays a crucial role in improving the film growth, surface chemistry, and mitigation of trap centers.