An alternative route towards low-cost Cu₂ZnSnS₄ thin film solar cells

Highlights

• CZTS thin films are prepared by a non-vacuum and low-cost process.

• Cu–Zn–Sn composite oxide with proper composition and particle size was obtained.

• CZTS phase can be formed via sulfurization of Cu–Zn–Sn composite oxide.

Abstract

A non-vacuum and low-cost route to fabrication of Cu₂ZnSnS₄ (CZTS) thin film as absorber layer for thin film solar cell is demonstrated. The process involves synthesis of Cu–Zn–Sn composite oxide nanoparticles, preparation of composite oxide ink, deposition of composite oxide thin film and subsequent sulfurization treatment. Cu–Zn–Sn composite oxide nanoparticles with proper composition and particle size can be obtained by controlling the chemical co-precipitation conditions. The effects of sulfurization temperature on the compositional, structural, morphological, optical and electrical properties of the CZTS thin films were investigated. XRD, Raman and X-ray photoelectron spectroscopy analyses confirmed the formation of CZTS phase after sulfurization. The prepared CZTS thin films exhibit porous morphology and an optical band gap about 1.35 eV. The solar cells fabricated with the CZTS thin film sulfurized at 550 °C showed a conversion efficiency of 1.22%.