Synthesis and physical properties of solar material Cu_1+x In_1‐x Se₂

Abstract

Bulk samples of Cu_1+x In_1‐x Se₂ (x  = 0–0.5) have been prepared by solid‐state reaction method at 1073 K. The crystal structure, thermal stability, optical absorbance and electrical properties were systematically studied. With the value x increasing from 0 to 0.5, the optical band gap is gradually reduced from 0.90 to 0.86 eV, moreover, the room temperature electrical conductivity has been greatly enhanced from 5 to 850 S/cm, but the Seebeck coefficient is slightly decreased from 80 to 57 µV/K even at 625 K. It is likely that lattice distortions, additional holes, and/or second phase introduced by Cu doping lead to these changes.