Electronic Properties and Carrier Trapping in Bi and Mn Co-doped CsPbCl₃ Perovskite

Metal halide perovskites exhibit impressive optoelectronic properties with applications in solar cells and light-emitting diodes. Co-doping the high-band gap CsPbCl₃ perovskite with Bi and Mn enhances both material stability and luminescence, providing emission on a wide spectral range. To discuss the role of Bi³⁺ and Mn²⁺ dopants in tuning the CsPbCl₃ perovskite energy levels and their involvement in carrier trapping, we report state-of-the-art hybrid density functional theory calculations, including spin-orbit coupling. We show that co-doping the perovskite with Bi and Mn delivers essentially the sum of the electronic properties of the single dopants, with no significant interaction or the preferential mutual location of them. Furthermore, we identify the structural features and energetics of transitions of electrons trapped at Bi and holes trapped at Mn dopant ions, respectively, and discuss their possible role in determining the optical properties of the co-doped perovskite.