Synthesis of reduced graphene oxide-copper tin sulphide composites and their photoconductivity enhancement for photovoltaic applications

Graphene-based composites are attractive to effectively tune the intrinsic properties of inorganic semiconductors. We report the first study of band gap tuning and photoconductivity enhancement of reduced graphene oxide-Cu2SnS3 (G-CTS) composite. A simple solvothermal route has been used to synthesize G-CTS with and without a complexing agent in the reaction mixture. Raman and FTIR studies confirm the formation of G-CTS and reduced graphene oxide-Cu2SnS3 by the addition of complexing agent ethylenediaminetetraacetic acid (G-CTS(E)) during synthesis. Powder X-ray diffraction reveals the formation of cubic CTS structure in both the composites. Scanning electron microscopy (SEM) study has revealed microbar and nanorod morphologies in the composites. The wide absorption of composites has been measured using absorption spectroscopy study. The band gaps of G-CTS and G-CTS(E) have been calculated using the absorption spectra and found to be 1.33 and 1.61 eV, respectively. This study confirms the suitability of G-CTS and G-CTS(E) for photovoltaic applications. Photoconductivity study reveals that G-CTS(E) generates 60 % more current than G-CTS.