First-principles calculation of stability, electronic and optical properties of PCBM-adsorbed MAPbI3 surface

Perovskite solar cells based on MAPbI(3) photosensitive material and PCBM electron transport layer demonstrated impressive performance with respect to superior stability and much higher charge carrier mobility. Clean MAPbI(3) (100) and PCBM-adsorbed MAPbI(3) (100) surfaces? stability, adsorption energy, electronic and optical absorption properties were investigated by the first-principles calculation. Due to the asymmetry of PCBM structure, the influence of different molecular orientations on the stability of adsorption structure was studied and the most stable structure with the adsorption energy ?0.87 eV per PCBM molecule was selected for further study. The electronic characteristic by the density of states show that not only the clean MAPbI(3) surface but also the PCBM-adsorbed MAPbI(3) surface has no surface state, which is a good explanation for the improvement of the solar cells? photovoltaic efficiency. From the charge density difference and Bader charge analysis, it was found that most atoms at the adsorbed surface have significant charge transfer.