Proceedings of Perovskite Thin Film Photovoltaics (ABXPV17)
Publication date: 18th December 2016
Organic-inorganic lead halide perovskites (mainly CH3NH3PbI3) are being extensively studied because their excellent photovoltaic properties, such as suitable bandgap, high optical absorption and long carrier lifetime. To improve their photovoltaic performance, it is important to understand the impact of point defects on their electronic structure. In this work, we report the electronic structure of new CH3NH3PbI3 perovskite derivatives, in which deep defects were obtained by replacing Pb+2 atoms. To deal with the bandgap underestimation problem of common DFT methods, quasiparticle calculations have been applied via the G0W0 approximation. Bandgap value based on GW has considerably improved theoretical results compared to experimental one for the native perovskite. The investigation of the electronic structure of new CH3NH3PbI3 perovskites suggests that the presence of point defects play an important role in the coupling of two low energy photons to achieve a higher energy electron excitation (like in the Z-scheme of photosynthesis), which would maximize the photovoltaic performance.
Acknowledgements. This work was partially supported by the Comunidad de Madrid project MADRID-PV (S2013/MAE/2780) and by the Ministerio de Economía y Competitividad through the project BOOSTER (ENE2013-46624-C4-2-R). The authors acknowledge the computer resources and technical assistance provided by the Centro de Supercomputación and Visualización de Madrid (CeSViMa).