Influence of chromium hyperdoping on the electronic structure of CH₃NH₃PbI₃ perovskite: a first-principles insight

Organic-inorganic hybrid halide perovskites compounds are emerging as new materials with great potential for efficient solar cells. This paper explores the possibility of increasing their photovoltaic efficiency through sub-bandgap absorption by way of the in gap band (IGB) concept. Thus, we assess the formation of an in gap band as well as its effect on the absorption features of Organic-inorganic hybrid halide perovskites CH₃NH₃PbI₃ (MAPI). For this task, we use density functional theory (DFT) as well as many-body perturbation methods along to spin-orbit coupling (SOC) to study structural, energetic and electronic properties of partially Cr-substituted MAPI perovskites (CH₃NH₃Pb_1-xCr_xI₃). Our results reveal that Cr replacement does not lead to an important cell distortion, while the energetic of the substitution process evidences the possibility of obtaining Cr-substituted perovskite. The analysis of the electronic structure shows that Cr 3d-orbitals induce new electronic states in the host semiconductor bandgap, which fulfill the requirements to be considered as an IGB. Precise many-body perturbation methods in G₀W₀ approach provided an accurate description on the electronic structures as well as the position of the IGB. In short, Pb replacement by Cr could be useful for improved absorption features through new sub-bandgap transitions across the in gap band.