Enhancement of Solar Energy Absorption and Optoelectronic Properties of SrCuSbS₃ by Lead Doping

Abstract

Copper antimony sulfides (CAS) are of great interest for their applications in solar absorbers. Here, a new series of CAS materials is reported, namely the Sr 1− x Pb x CuSbS 3 ( x = 0–0.2), which are synthesized via solid state reactions. The new compound SrCuSbS 3 crystallizes in the orthorhombic space group Pbam and consists of 3D [CuSbS 3 ] 2− extended framework and Sr 2+ ions. The [CuSbS 3 ] 2− framework is constructed by [CuS 3 ] 5− one‐dimensional chains and [SbS 3 ] 3− triangular pyramids. The compound is a semiconductor with a band gap of 1.91 eV. Partial replacement of Sr 2+ by Pb 2+ can narrow the band gap to 1.63 eV when the doping concentration is up to 20%. First‐principles calculations reveal that the SrCuSbS 3 compound is a direct band gap semiconductor with the valence band maximum composed of Cu‐3 d states and the conduction band minimum composed of Sb‐5 p ‐S‐3 p states. The Pb orbitals play critical roles in narrowing the band gap of Sr 1‐ x Pb x CuSbS 3 ( x = 0–0.2). The series of CAS materials also show evident photoelectric response properties which demonstrate their potential for applications for photovoltaic devices. In addition, these CAS materials are good photocatalysts for the photodegradation reaction of Rhodamine B (RhB). The Sr 0.8 Pb 0.2 CuSbS 3 powder can degrade 100% of RhB within 3 h under simulated sunlight.