Stability Improvement of Methylammonium Lead Iodide Perovskite Thin Films by Bismuth Doping

Perovskites have been in the spotlight in the field of solar cells due to their high efficiency and their low cost of materials and fabrication processes. Perovskite solar cells (PSCs) have shown an efficiency of up to 25%. Nevertheless, PSCs have some drawbacks such as rapid degradation in ambient conditions. To improve PSC stability, lead is usually replaced with bismuth. In this article, we report the results when doping the methylammonium lead iodide (CH3NH3)PbI3, aka MAPbI(3), with different bismuth quantities. The incorporation of bismuth into the lattice leads to a remarkable change in optoelectronics and morphological structure. Substituting lead atoms with 2% bismuth improves some characteristics of MAPbI(3) layers, such as removing pinholes and increasing crystallite size and optical absorption. Furthermore, bismuth doping improves the stability of pure MAPbI(3) layers, which after 4 weeks exhibits higher degradation compared to bismuth-doped MAPbI(3) samples, which remain stable after that period.