Synthesis, crystal structure, electronic structure, and photoelectric response properties of KCu2SbS3

Abstract

Copper thioantimonates have received enormous attention due to their potential for applications in photovoltaic devices. In this work, a new layered compound KCu₂SbS₃ was synthesized via a reactive flux method using thiourea as a reactive flux. The compound crystallizes in the triclinic space group P. The structure features two-dimensional [Cu₂SbS₃]⁻ layers stacking along the c axis with K⁺ ions intercalated between the layers. Each [Cu₂SbS₃]⁻ layer is composed of two single graphene-like layers connected via interlayer Cu–S bonds and Cu⋯Sb contacts. The optical measurements indicate that the compound has a band gap of 1.7 eV. The Hall effect measurement shows that KCu₂SbS₃ is a p-type semiconductor with a carrier concentration of 7 × 10¹⁶ cm⁻³. First-principles calculations reveal that the direct transition occurs between Cu-3d–S-3p orbitals (VBM) to Sb-5p–S-3p orbitals (CBM). The photoelectric response properties of KCu₂SbS₃ under visible light irradiation were analyzed. The photocurrent is 3.7 μA cm⁻² at 10 V bias, demonstrating its potential for applications in photoelectric devices.