Predicting the Inorganic Exciton Peak Position in 2D Hybrid Organic-Inorganic Perovskites from Hybrid Density Functional Theory

Modelling the inorganic exciton contribution to 2D hybrid organic-inorganic perovskites is essential to understand their properties and screen for new materials. Here, we combine hybrid density functional theory calculations including spin orbit coupling (SOC) with the experimental relationship between the inorganic band gap and exciton binding energy to predict the inorganic exciton energy. For this purpose, we determine a universal exchange parameter for the HSE06 hybrid functional with SOC for lead-based 2D hybrid organic-inorganic perovskites. We further identify a relationship that connects PBE calculations to experiment-quality optical gaps and allows us to generalize the exchange mixing parameter other SOC approximations. Our approach opens the path to screen for 2D hybrid organic-inorganic perovskites with optimized spectra, e.g., for new solar cell or light emitting materials.