Ab-initio study of formamidinium lead halide (FAPbX3, X = Br, Cl) perovskite’s monolayers

Here the density functional theory (DFT) based analysis of formamidinium lead halide (FAPbX3 (X = Br, Cl)) monolayers is carried out. The FAPbBr3 and FAPbCl3 monolayers are direct bandgap semiconductors consisting of energy gap of 2.60 eV and 3.10 eV, respectively. Cohesive energies of FAPbBr3 and FAPbCl3 monolayers came to be −5.31 eV/atom and −5.43 eV/atom, respectively, which depicts stability of our monolayers. The static dielectric constants (εr(0)) for FAPbBr3 and FAPbCl3 monolayers are 1.59 and 1.46, respectively. Also, the FAPbBr3 and FAPbCl3 monolayers show static reflectivity around 1.3% and 0.9%, respectively. We have also investigated solar cell parameters of these monolayers using Shockley-Queisser (SQ) limit. The efficiency (η) of FAPbBr3 and FAPbCl3 came to be around 10.75% and 3.48%, respectively. Also, FAPbBr3 and FAPbCl3 tends to show impressive values of open circuit voltage (Voc) about 2.21 eV and 2.71 eV, respectively.