Mechanical Properties of the Tetragonal CH3NH3PbI3 Structure

The hybrid organic-inorganic halide perovskite solar cells based on CH3NH3PbI3 have attracted enormous attention in the last few years due to their rapid improvement and high certified efficiencies over 20%. In this paper, the tetragonal structure of CH3NH3PbI3 hydrides was investigated by first-principles calculations based on density functional theory (DFT) with the generalized gradient approximation (GGA). The elastic constants for the tetragonal CH3NH3PbI3 hydride are successfully obtained from the stress-strain relationship calculations. The obtained equilibrium lattice parameters and elastic constant (Cij) are in good agreement with other theoretical values and experimental data available in the literature. The shear modulus (G), bulk modulus (B), Young’s modulus (E), Poisson’s ratio (ν) and the ratios (B/G) are also determined. The calculated bulk modulus and the ductility factor (B/G) shows that the CH3NH3PbI3 hydrides which indicates that this material is ductile behaviour. Also, the universal Poisson’s ratio (ν) is higher than the critical value.