Graphene/TiO2 nanocomposite electrodes sensitized with tin sulfide quantum dots for energy issues

In this work, graphene (Gr)/TiO2 nanocomposite electrodes sensitized with tin sulfide quantum dots (SnS QDs) for energy issues have been investigated. Different sizes of SnS QDs as non-toxic and earth-abundant semiconducting materials are synthesized onto Gr/TiO2 nanocomposite electrodes using successive ionic layer adsorption and reaction (SILAR) technique for "n" cycles (n: 1 to 8). The structural properties of the prepared SnS(n) QDs photoanodes are studied using an X-ray diffractometer. The XRD measurements ensure the formation of the crystalline structure of orthorhombic SnS QDs. The optical properties of the synthesized SnS(n) QDs photoanodes are characterized using a UV–visible spectrophotometer. The estimated direct (indirect) energy band gap (Eg) of the prepared SnS(n) photoanodes is tuned from 2.36 (1.57) eV to 1.76 (1.30) eV by controlling the number of SILAR cycles from 1 to 8. The photovoltaic performance of the assembled SnS(n) quantum dots sensitized solar cells (QDSSCs) has been studied under a solar power illumination of AM1.5 conditions. The optimal photovoltaic performance of the assembled SnS(n) QDSSCs is achieved at 6 SILAR deposition cycles. As compared with previous studies, enhancement of 48% in the energy conversion efficiency η has been achieved due to the active Gr incorporation. SnS(n) QDSSCs shows high reproducibility and sensitivity undercutting ON-OFF the solar illumination. Gr plays the role of kids slide for the photo-generated electrons and facilitates their transportation.