Flexible and efficient semiempirical DFTB parameters for electronic structure prediction of 3D, 2D iodide perovskites and heterostructures

Density Functional Tight Binding (DFTB), an approximative approach derived from Density Functional Theory (DFT), has the potential to pave the way for simulations of large periodic or nonperiodic systems. We have specifically tailored DFTB parameters to enhance the accuracy of electronic band gap calculations in both three-dimensional and two-dimensional lead-iodide perovskites, at a significantly reduced computational cost relative to state-of-the-art ab initio calculations. Our electronic DFTB parameters allow computing not only the band gap but also effective masses of perovskite materials with reasonable accuracy compared to existing experimental data and state-of-the-art DFT calculations. The electronic band structures of vacancy-ordered and lead- and iodide-deficient perovskites are also explored. Additionally, we demonstrate the efficiency of DFTB in computing electronic band alignments in perovskite heterostructures. The DFTB-based approach is anticipated to be beneficial for studying large-scale systems such as heterostructures and nanocrystals.