Rational design of mixed Sn–Ge based hybrid halide perovskites for optoelectronic applications: a first principles study

Here, we have investigated some mixed metal hybrid halide perovskite materials by employing first principle calculation method. In this regard we have designed some Sn and Ge based hybrid halide (iodide) perovskite materials incorporating dimethylammonium (DMA) organic cation and studied their structural, optoelectronic and photovoltaic properties. Observed tolerance factor (TF) and dihedral factor (μ) manifests that our studied compounds form stable three dimensional perovskite structure. Additionally, the observed negative value of formation energy indicates their thermodynamic stability. Calculated band gap values indicate the semiconducting nature of the compounds. We have also calculated the real and imaginary part of dielectric function as well as absorption coefficient of all the studied compounds. Our investigation reveals that compounds with equal amount of Sn and Ge content exhibit higher value of dielectric function and absorption coefficient among the studied compounds. Study of photovoltaic performances reveal that DMASn(0.75)Ge(0.25)I(3) exhibits the highest value of theoretical power conversion efficiency (PCE) i.e., 17.42% among the studied compounds. This investigation will help researchers to design Pb-free hybrid perovskite materials which will be beneficial for the world.