Low-temperature synthesis of Cu2CoSnS4 nanoparticles by thermal decomposition of metal precursors and the study of its structural, optical and electrical properties for photovoltaic applications

Abstract

Copper-based chalcogenide quaternary semiconductors Cu₂CoSnS₄ (CCTS) have emerged as a promising material for thin film photovoltaic devices due to their opto-electrical properties and earth-abundant composition. The present study reports the synthesis of CCTS nanoparticles by a robust, solvent free, single step thermal decomposition process and their application in photovoltaics. Detailed studies of the effect of synthesis parameters (temperature, time) on crystallization, and the elemental composition of CCTS nanoparticles are reported. Physical, optical and electrical characterization of the as-synthesized nanoparticles and sulfurized films were carried out. The morphology and elemental composition of the synthesized nanoparticles are found to be similar to the nanoparticles synthesized by conventional solution processes. Electrical properties of the CCTS films are reported for the first time and are found to be carrier mobility (µ) = 36 cm² V⁻¹ s⁻¹, carrier concentration (n) = 2 × 10¹⁶ cm⁻³, resistivity = 3 × 10⁻³ Ω m. Mott–Schottky analysis confirmed the p-type conductivity of the CCTS film. The films fabricated from the as-synthesized nanoparticles showed a photoresponse under illumination (100 mW cm⁻²). The optimum optical band gap (1.46 eV) and photoresponse of the CCTS film indicate that it can act as a promising cost-effective absorber layer for thin film solar cells.