First-Principles Study on Electronic Structures of FAPbX3 (X = Cl, Br, I) Hybrid Perovskites

Using first principles calculations, we investigate the geometric and electronic structures of organic-inorganic hybrid perovskite, FAPbX 3 (FA = CH(NH 2 ) 2 + ; X = Cl, Br, I). Since the organic molecule in the centre of the 3D hybrid perovskite is the key for its characteristics, here we compare FAPbX 3 with MAPbX 3 (MA = CH 3 NH 3 + ). The band gap of the former is smaller than the latter. Particularly, the calculated band gap of FAPbI 3 , 1.40 eV, is close to the experimental data, 1.41 eV. Furthermore, we analyze their orbitals, density of states and the spatial distribution of the charges, revealing that FAPbX 3 can produce and transfer more excitons than MAPbX 3 does.