DFT study of the structural, electronic and optoelectronic properties of PDAPb(I_1−xBr _x )₄ perovskites

Abstract PDAPb(I 1− x Br x ) 4 (NH 3 CH 2 CH 2 CH 2 NH 3 Pb(I 1− x Br x ) 4 , 0 ⩽ x ⩽ 1) is a two-dimensional Dion–Jacobson phase perovskite that has attracted extensive attention owing to its potential as a promising candidate for optoelectronic (OE) application. Herein, the structural, electronic, and optoelectronic properties of PDAPb(I 1− x Br x ) 4 by gradually substituting I with Br at 1/4 intervals starting from PDAPbI 4 based on the first-principles approach of density functional theory. With the increase in Br content, the crystal volume of PDAPb(I 1− x Br x ) 4 decreases nonlinearly. The electronic structure shows the bandgap presents an increasing trend (PDAPbI 4 (2.272 eV)–PDAPb(I 0.5 Br 0.5 ) 4 (2.475 eV)–PDAPbBr 4 (2.678 eV)). The most stable structure that can be obtained from the calculated formation energy ( E f ) is PDAPb(I 0.5 Br 0.5 ) 4 . The partial density of states reveals that the contribution of electrons is mainly related to the [PbX 6 ] 4− (X = I, Br) octahedron. The organic molecule PDA is almost not involved in the conductivity. The optoelectronic properties indicates that the characteristic peaks of the optoelectronic parameters of PDAPb(I 1− x Br x ) 4 coincide with the bandgap. The doping ratio of 0.5 not only has the largest dielectric coefficient, but also has good conductivity in the visible region. Therefore, PDAPb(I 0.5 Br 0.5 ) 4 is extremely promising for applications in OE industry. This study provides some theoretical guidance for experiments and the search for new efficient and environmentally friendly OE materials.