Temperature dependent growth of Cu2SnS3 thin films using ultrasonic spray pyrolysis for solar cell absorber layer and photocatalytic application

Abstract

Ternary chalcogenide Cu2SnS3 (CTS) thin films are deposited on glass substrates using low cost ultrasonic spray pyrolysis (USP) technique by varying substrate temperatures 300 °C to 550 °C. Crystal structure of CTS thin film is found to change its phase from amorphous to tetragonal phase with increase in substrate temperature. Properties of as-deposited Cu2SnS3 thin films are studied using various characterization techniques. X-ray powder diffraction (XRD) studies confirm the formation of Cu2SnS3 tetragonal phase with orientation along (112) plane with increase in substrate temperature. Raman analysis revealed the formation of binary phase at 550 °C substrate temperature. Increase in substrate temperature resulted in stoichiometric nature of Cu2SnS3 films at 500 °C. The absorption coefficient of CTS films is found to be ∼105 cm−1 with band gap ranging from 1.35 eV to 1.48 eV. Electrical properties of CTS films exhibited p type conductivity with carrier concentration of the order of 1021 cm−3. The resistivity of the CTS films is found to vary from 1.5 × 10−3 to 3.2 × 10−3 Ω-cm. Photocatalytic effect of optimized Cu2SnS3 thin film under visible light (300 W) is examined with methylene blue (MB) dye and ∼90% MB is degraded under 3 hours visible light irradiation. The above properties indicate that Cu2SnS3 is a potential candidate to be used for solar cell absorber layer and photocatalytic activity.