Lead-free double perovskite Cs₂AgBiBr₆ has garnered significant attention in the field of nuclear radiation detection as an environmentally friendly material. Experimental observations have revealed that doping Cs₂AgBiBr₆ with Cu⁺ significantly enhances the material's stability and photoelectric conversion efficiency.

This study aims to investigate the impact of Cu⁺ doping on the crystal structure and electrical properties of Cs₂AgBiBr₆.

Based on density functional theory, first-principles calculations were applied to exploring the effects of Cu⁺ doping on the structure and electrical properties of Cs₂AgBiBr₆. Structural properties, such as the stability, doping formation energy, lattice parameters, elastic constants, of Cu⁺ doping on the lead-free double perovskite Cs₂AgBiBr₆ were investigated by simulation whilst the band analysis and density of states analysis were employed to study the impact of electrical performance.

The results indicate that Cu⁺ doping enhances the stability of Cs₂AgBiBr₆. The Cs₂Ag_1-xCu_xBiBr₆ compounds formed by doping, as well as the original Cs₂AgBiBr₆ material, exhibit indirect bandgap semiconductor behavior. The bandgap significantly narrows with an increase in the Cu⁺ doping ratio. Based on an analysis of the density of states (DOS), the bandgap narrowing can be attributed to the downward shift of the conduction band minimum dominated by Bi6p orbitals due to Cu⁺ doping.

Cs₂Ag_1-xCu_xBiBr₆ exhibits greater stability and superior electrical properties compared to Cs₂AgBiBr₆, making it a promising candidate material for semiconductor radiation detectors.