Journal for Foundations and Applications of Physics
Abstract
Although methyl ammonium lead iodide, (CH3NH3PbI3) has proven to be an effective photovoltaic material, there remains a main concern about the toxicity of lead, therefore determination of a lead free halide perovskite is of outstanding interest. Sn2+ metal cations are the most obvious substitute for Pb2+ in the perovskite structure because of the similar s2 valence electronic configuration to Pb2+. Sn2+ can form a perovskite with a basic formula ASnX3 (A= CH3NH3 and X = halide) because the ionic radius of Sn2+ is similar to that of Pb2+. With the above similarity, methyl ammonium tin iodide CH3NH3SnI3 is one of the common replacement for CH3NH3PbI3 in the fabrication of organic-inorganic perovskite solar cells. FHI-aims code was used to perform the simulation of CH3NH3SnI3 in this work. Geometry building, parameter optimization, determination of the best exchange functional, k-grid convergence test along with determination of equilibrium lattice constant and geometry relaxation for CH3NH3SnI3 were carried out. An energy direct band gap of 1.051 eV was obtained, with an underestimation of 0.249 eV which amount to 19.2% when compared with experimental value. The lattice constant obtained using phonopy with ZPE is close to experimental reported values with an underestimation of 3.01%. The temperature dependent of lattice constant was studied in the temperature range of 0 to 318 K. At the same temperature range, shift in energy bandgap and dielectric constant due to lattice expansion was also investigated
