Photoelectric properties of cubic mixed-cation lead halide perovskites (Cs MA1-PbI3) from first-principles

Recently, hybrid cationic perovskite solar cells (PSC) have attracted much attention because of their higher stability and better photovoltage performance than pure ABX 3 perovskite solar cells. Methylammonium lead iodide (MAPbI 3 ) is one of the most widely studied perovskite solar cell materials. However, the instability of organic cations has become the main obstacle to its commercialization. Here, we address the issues of forming a photostable MA-based perovskite by partially substituting the methylammonium with cesium ions (Cs x MA 1- x PbI 3 ). Its structure and photoelectric properties are studied by first-principles calculation method. The results show that the phase stability of MAPbI 3 can be improved for appropriate concentration of cesium ion. In addition, the band gap decreases with the increase of the proportion of doped cesium ions. Cs x MA 1- x PbI 3 maintains the basic characteristics of MAPbI 3 and has better thermodynamic stability, carrier mobility and light absorption characteristics in the case of small amount of Cs doping, which make it a candidate material for high-efficiency perovskite solar cells. • Cs-doped MAPbI 3 increases the thermal stability. • Cs-doped MAPbI 3 has a better band gap value, which is conducive to the visible light absorption in solar cells. • The doped material has higher carrier mobility and visible light absorption coefficient