Electronic Structure Panorama of Halide Perovskites: Approximated DFT-1/2 Quasiparticle and Relativistic Corrections
Fernando Valadares, Ivan Guilhon, L. K. Teles, Marcelo Marques
Abstract
Halide perovskite compounds emerged recently as great candidates for efficient photovoltaics, although huge technical obstacles still have to be overcome. Additionally, their accurate theoretical description is difficult to be reached due to the high level of complexity of this class of materials. In this work, we provide a vast panorama of electronic properties, correlated with its relaxed internal geometry, for a group of 48 ABX3 cubic halide perovskites (A = CH3NH3, CH(NH2)2, Cs, Rb; B = Pb, Sn, Ge, Si; X = I, Br, Cl). Including the DFT-1/2 approximated quasiparticle and spin–orbit corrections, our model results in band gaps with an impressive agreement with experiments, comparable with the expensive state-of-the-art GW method. We provide trends in electronic properties depending on different atoms exchanged, concluding that 16 materials present band gaps more suitable for solar cell applications. Besides, the formation of BX3 units is observed in hybrid Sn, Ge, and Si perovskites, resulting from the distortion of the inorganic lattice. We elucidate the significant band gap broadening due to this segregation using orbital overlap considerations, which is consistent with previous experimental findings. Finally, the presented method establishes a reliable low-cost approach, being especially useful for more sophisticated perovskite systems as heterostructures, alloys, and low symmetric compounds.