Our group has been successful in applying Quantum Mechanics (QM) methods, such as, DFT in studying the materials class of metal halide perosvkites (18 pristine compounds in total). However, DFT is computationally demanding and often limited to small and pure systems. Simulation of dynamic processes, such as ion migration and degradation reactions in MHP alloys is beyond the capacity of DFT. Classical Molecular Dynamics (CMD) does not suffer from the limitations of DFT and can handle larger systems. However, CMD cannot describe electrons. Consequently, CMD is not suited for studying the chemical reactions and electronic properties of MHP.
We meet this challenge in this project by combing the functionalities of describing both electrons and ions in a Semi-empirical QM method, such as, Density Functional Tight Binding method (DFTB).
The goal of this project is to develop new sets of atomic potentials (parameter fitting) dedicated for large-scale simulations (up to 1.000 to 10.000 atoms) of complex metal halide perovskite alloys. We have obtained satisfactory potentials for CsPbI3 and CsPbBr3.
A first project will be an extension to other 16 compounds, namely, from Cs to MA to FA, from Pb to Sn, from I/Br to Cl.
A second project would be extending the study of pure perovskites to alloys (making the potential parameters transferable), i.e. to simulate CsPb(IxBr1-x)3.