First-principles study on CH3NH3PbI3 materials for perovskite solar cells

CH3NH3PbI3 system of organic-inorganic hybrid perovskite structure solar cells absorption material was established by using first-principle calculations based on density functional theory (DFT). Orthorhombic CH3NH3PbI3 system model is optimized by different functional theories of CASTEP in Materials Studio. It revealed that the results of WC/GGA calculation method are more close to the experimental value. Electron band structure, state density are calculated in the paper and the results indicated that top orbital of the valence band is mainly contributed by Pb atom and I atomic orbital. At the same time, the conduction band bottom is mainly contributed by the orbital contribution of Pb atoms and strong σ bond is formed between terminal iodine atom and Pb atomic orbital. Moreover, the contribution of organic element density of states near the Fermi surface is very weak and the band gap of organic-inorganic hybrid CH3NH3PbI3 materials is basically determined by inorganic elements.