Designing wide bandgap halide perovskite materials by introducing dications

Abstract In recent years, halide perovskites have made great progress due to their excellent optoelectronic properties. Taking advantage of the excellent elemental tunability of perovskites, a novel perovskite is designed as DAPPb 2 I 6 , where DAP indicates NH 3 (CH 2 ) 5 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">NH</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> The geometry, stability, electronic structure, and optical properties of DAPPb 2 I 6 are investigated based on first principles calculations. Doping effects are taken into account by replacing I by Br. The ab initio molecular dynamics (AIMD) simulations show that these materials have high thermodynamic stability at room temperature. All DAPPb 2 (I 1- x Br x ) 6 have indirect bandgaps with the calculated values of 2.22–2.72 eV, indicating that introducing of DAP increase the bandgap remarkably. The conduction bands are mainly contributed by Pb atoms, followed by halogen atoms, while the valence band part is mainly contributed by halogen atoms. These materials have high remarkable light absorption capacity with light absorption coefficients up to 4.5 × 10 5 cm −1 with wavelengths in the range of 200–450 nm. Doping of Br can increase the bandgap values and the cause blue-shift of the light adsorption. The newly designed DAPPb 2 (I 1- x Br x ) 6 may serve as a promising wide bandgap perovskite material.