The predictive power of “one-shot” GW calculations for halide perovskites*

Halide perovskites like the hybrid organic-inorganic APbX₃ (A=CH₃NH₃⁺, CH(NH₂)₂⁺,... and X=I, Br, Cl) or the all-inorganic double perovskite Cs₂BiAgBr₆ are a class of compounds showing great promise as photovoltaic absorber materials. Accurately predicting their band gaps is challenging for first principles electronic structure methods because of the intricate coupling of structural and electronic degrees of freedom [1] as well as strong spin-orbit interactions. We use ab initio many-body perturbation theory, employing a “one-shot” G₀W₀ approach, to calculate the fundamental band gaps of experimentally characterized halide perovskites. We investigate the impact of the density functional theory starting point, pseudopotentials, and eigenvalue self-consistency on the calculated quasiparticle band gap. With our calculations, we assess whether there might be a “one size fits all” one-shot GW approach for this material class [2].

[1] L. Leppert, S. Reyes-Lillo, J. B. Neaton, J. Phys. Chem. Lett. 7, 3683 (2016). [2] L. Leppert, T. Rangel, J. Haber, J. B. Neaton, in preparation (2017).