Calculating band gap distributions of halide perovskites with a first-principles tight-binding approach

Halide perovskites (HaPs) exhibit intriguing optoelectronic properties that cannot yet be fully explained on a microscopic level. Understanding the characteristics of HaPs is possible with well-established conventional theoretical calculations, such as density functional theory (DFT), but their applicability to large-scale simulations is often limited by their computational costs. Here, building on previous work [1] we put forward a tight binding (TB) approach as a computationally efficient tool to model large-scale system sizes and calculate optoelectronic properties of HaPs. Parametrizing the TB model with DFT calculations and unifying it with force-field molecular dynamics, we compute dynamic band gap distributions for several HaPs as well as their dependence on temperature. This helps resolving confluences of small Urbach energies and large amounts of nuclear disorder in HaPs around room temperature.



References
[1] M. Z. Mayers, L. Z. Tan, D. A. Egger, A. M. Rappe and D. R. Reichman. How Lattice and Charge Fluctuations Control Carrier Dynamics in Halide Perovskites. Nano Lett. 18, 8041 – 8046 (2018).