Effect of metal (Ag and Cd) substitution on methylammonium lead iodideperovskiteMAPbI3optoelectronic properties for photovoltaic applications

Abstract

Abstract Organometallic perovskite (OMHP) based solar cells, with higher than 24% of power conversion efficiency (PCE), attract special attention. High absorption coefficient is a property of such OMHPs. In this work the organometallic halide perovskite, methylamunium lead iodide (MAPbI3), is partially substituted with two Ag and Cd atoms. The effect of substitution on structural and optoelectronic properties of the perovskite is studied, based on the ab-initio DFT method. Properties of MAPbI3 andMAABxPb1-xI3(Bx = Ag0.17 or Cd0.5) perovskites, in their orthorhombic phase, are described. The energy band gaps are calculated here with PBE-GGA and HSE06 methods. The MAPbI3 is characterized by its high absorption coefficient over the visible spectrum [1.65–3.26 eV: 750- 380 nm] compared to MAAg0.17Pb0.83I3 (α = 104–0.6 × 105cm−1), and MACd0.5Pb0.5I3 (α = 1.5 × 104 – 0.4 × 105cm−1). Low anisotropic electron and hole effective masses are calculated for all compounds in the range of 0.043 m0-0.188 m0. The anisotropy in optical properties for MACd0.5Pb0.5I3, such as the absorption coefficient α, the dielectric constant e and the refractive index n, is noticed. Enhancement in refractive index n of MAAg0.17Pb0.83I3is also observed. The calculated values for n are 2.90, 2.75 and 2.00 for MAAg0.17Pb0.83I3, MAPbI3 and MACd0.5Pb0.5I3, respectively, at 2.5 eV energy peak value. The values for κ are 1.4, 1.8, and 1.2 for MAAg0.17Pb0.83I3, MAPbI3 and MACd0.5Pb0.5I3, respectively, at 3.5 eV energy peak value.