Photovoltaic and related properties of Sn-doped disordered CsPbxSn1−xBr3 perovskite: a first-principles calculation.

Perovskite CsPbBr₃ possesses high photovoltaic capability but limited application on account of the toxicity of lead. Sn-doped all-inorganic perovskites CsPb_xSn_1−xBr₃ are designed in order to achieve comprehensive high photovoltaic performance with low toxicity, which is under great influence of chemical compositions and defects. In this paper, the electronic structures and other photovoltaic-related properties of CsPbBr₃ and CsSnBr₃ are studied by using first-principles method with different functionals. The calculation results show that CsSnBr₃ has a lower bandgap than that of CsPbBr₃. The transition dipole moment of CsPbBr₃ is more even, and the effective masses of electrons and holes are slightly larger than those of CsSnBr₃. By calculating the defect formation energies, the types and properties of intrinsic defects of these two crystals are compared, and their effects on photovoltaic-related properties are analyzed. Different proportions of disordered CsPb_xSn_1−xBr₃ crystals constructed by special Quasirandom structure (SQS) method are designed to observe the effect of Sn contents on the electronic structure, and effective masses of electrons and holes of CsPbBr₃, and CsPb_0.50(Ba/Ca)_0.50Br₃ are also calculated as a reference. It has been proved that the presence of Sn affects the orbital composition at the valence band maximum of the crystal, making Sn-5s orbitals participate in the formation of valence band maximum, which raises the energy of crystal valence band maximum and reduces the bandgap of the system. The doping of Sn decreases the toxicity of perovskite on the premise of considering the power conversion efficiency, which may provide a theoretical basis for the development of CsPb_xSn_1−xBr₃ photovoltaic materials. [ABSTRACT FROM AUTHOR]