DFT-Based exploration of Mo substitution in RbPbCl3 and RbSnCl3 : Transition Metal tuning of halide perovskite properties

First-principles calculations under doping in the DFT framework were used to investigate the structural, mechanical, thermal, and electronic properties of lead-free and lead-containing halide perovskites, Rb X Cl₃ ( X  = Pb, Sn). The impact of Mo doping on these characteristics of Rb X Cl₃ ( X  = Pb, Sn) perovskites is investigated using DFT. The compounds exhibit structural stability in their optimal state in each case, as determined by the Born stability criteria. This entails computing the elastic constants, which show anisotropic as well as ductile qualities. However, the maximum ductility was observed for RbSn _0.875 Mo _0.125 Cl ₃ . It is observed that the materials RbSnCl ₃ , RbPbCl ₃ , and RbPb _0.875 Mo _0.125 Cl ₃ show band gaps of 0.877 eV, 2.180 eV, and 4.125 eV, respectively. However, there was no energy band gap in the metallic-behaving RbSn _0.875 Mo _0.125 Cl ₃ phase. As the temperature changed, anomalous properties were found for RbPbCl ₃ . It appears that doped samples are acceptable for thin-film production due to their lower bulk modulus value and high ductility. Based on a comprehensive comparison of pure and Mo-doped halide perovskites, it is revealed that RbSnCl ₃ is a more ecologically beneficial perovskite candidate for use in optoelectronic applications.