Structure, optical, and electrical properties of layered oxychalcogenide Sr2ZnCu2(S1−x Se x )2O2 (0 ≤ x ≤ 1) compounds

Layered oxychalcogenide Sr _2 ZnCu _2 (S _1- _x Se _x ) _2 O _2 compounds were synthesized via a solid-state reaction. Density functional theory calculations indicate different valence band maximum, Sr _2 ZnCu _2 Se _2 O _2 was composed of Cu 3 d –Se 4 p , while Sr _2 ZnCu _2 S _2 O _2 was dominated by the Zn 3 d –O 2 p hybrid orbital. Band gap was decreased as the Se-containing is increasing, from 2.5 eV to 2.2 eV. In contrast, electrical conductivity of the Se-substituted samples considerably increased from 10 ^−3 S cm ^−1 at x = 0 to 10 ^−1 S cm ^−1 at x = 0.25, and was almost the same at x = 1. Based on this feature, Sr _2 ZnCu _2 (S _1- _x Se _x ) _2 O _2 can be applied as a transparent conductor material.