Hybrid organic-inorganic perovskites such as the MAPbI3 (MA: methylammonia) have the potential to revolutionize the photovoltaics industry with their cost effectiveness and record high power conversion efficiencies (PCE) above 20%. However, current perovskite materials degrade over time when exposed to moisture and/or under continuous light illumination severely limiting their long term stability. Recently, it has been experimentally shown that two-dimensional (2D) forms of the hybrid perovskites (see figure) have improved stability, as compared to the hitherto investigated bulk structures, because the inorganic layers responsible for the light absorption are protected on both sides by the hydrophobic organic molecules. This makes the 2D hybrid perovskites extremely promising candidate materials for high-efficiency and ultra thin solar cells. The 2D perovskites represents one of the most recently discovered members of the class of atomically thin 2D materials, which began with the exfoliation of graphene, and today contains numerous compounds with diverse properties.
This project will use quantum mechanical simulations based mainly on density functional theory (DFT) to calculate the electronic and optical properties of the 2D hybrid perovskites and eventually to design completely new types of 2D perovskites with improved properties. Specifically, it will be investigated whether it is possible to tune the band gap and optical absorption spectrum, by varying the organic molecule using ideas from organic chemistry where it is well known that the energy levels of molecular complexes can be shifted up/down in energy by adding side groups with donating/accepting character. This idea will be used to design new hybrid perovskites with optimal band gaps tuned to match the solar spectrum.
The project is well connected to ongoing research activities both within CAMD and at the Center for Nanostructured Graphene (CNG); you will thus be part of a larger team of researchers working on 2D materials and electronic structure theory. The data produced and results obtained in the course of the project will also be beneficial for the 2D Materials Database developed and maintained at CAMD.
Knowledge of quantum mechanics