Effects of Br-Doped and Ligand-Symmetry on the Properties of APb(I1-xBrx)4 (A=PeDA/DPA) Perovskites

Abstract In this paper, the properties of perovskites based on symmetric (1,5-Pentanediamine (PeDA)) and asymmetric (1,4-pentanediamine (DPA)) ligands are systematically tuned by substituting I with Br. This paper employs the method of density functional theory to explore the characteristics of APb(I 1-x Br x ) 4 (A = PeDA/DPA; x = 0.00, 0.25, 0.50, 0.75, 1.00). The analysis reveals that bromine doping results in a noticeable reduction in the bond lengths within the metal-halide framework. The electronic structure analysis shows that with an increasing Br doping ratio, the bandgap of PeDAPb(I 1-x Br x ) 4 increases linearly from 2.88 eV to 3.64 eV, and DPAPb(I 1-x Br x ) 4 exhibits an overall upward trend from 2.31 eV to 3.49 eV. Optical property analysis demonstrates that when the ligand is DPA with a Br doping ratio of 0.50, the material exhibits excellent light absorption in the visible region.