Impact of fluorine on organic cation for determining the electronic and optical properties of CH3−xFxNH3PbI3 (x = 0, 1, 2, 3) hybrid perovskites-based photovoltaic devices

Abstract

Hybrid halide perovskite CH3NH3PbI3 is emerging as a promising solar cell material owing to its low-cost fabrication and remarkable optical and electronic properties. In this scrutiny, we examined the structural stability, electronic structures, and optical properties of a pure cubic MAPbI3 compound and the CH3−xFxNH3PbI3 (x = 0, 1, 2, 3) compounds derived by the substitutional impact of fluorine on the methylammonium (MA) organic cation. In our calculations, we employed the full-potential linear augmented plane wave (FP-LAPW) methodology within the generalized gradient approximation (GGA). From the minimization of total energy, the lattice parameter and formation energy of CH3−xFxNH3PbI3 (x = 0, 1, 2, 3) hybrid perovskites are computed. The results clearly revealed that the pure MAPbI3 is the most stable perovskite among other structures. The electronic properties determined from the electronic density of states depend quite significantly on the impact of fluorine of MA organic cation and inorganic component, i.e. [PbI6]−4. The important optical spectra (the complex dielectric function, complex refractive index, absorption coefficient, energy loss function, and reflectivity) are computed for the halide perovskites (CH3−xFxNH3PbI3, x = 0, 1, 2, 3) versus the photon energy. The values of the static dielectric constants and the static refractive index are found to diminish with the increasing of the number of fluorine atoms in MA cation. The electronic polarizability was also calculated for all the considered materials in the high frequency optical span. Interestingly, the high absorption coefficient (∼106 cm−1) and a band gap of around 1.6 eV render these hybrid perovskite materials to be prosperous for photovoltaic applications. For the various physical properties of pure CH3NH3PbI3 compound, a good consistency is found comparatively to the available experimental and theoretical results. Our findings are expected to be of great interest for future investigations.