Nanophase CulnS2 nanosheets/CuS composite grown by the SILAR method leads to high performance as a counter electrode in dye sensitized solar cells

Single phase CulnS(2) (CIS) nanosheets are synthesized on TiO2 coated FTO by the simple technique of Successive Ionic Layer Adsorption Reaction (SILAR) followed by annealing at 500 degrees C. Annealing at a lower temperature of 250 degrees C is found to yield CuS nanoparticles in addition to the CIS phase. Both single phase CIS and the CuS/CIS nanocomposite were examined as counter electrodes for a dye-sensitized solar cell (DSSC). The CIS-CuS composite is found to have a synergistic effect on the catalytic performance toward the reduction of tri-iodide, yielding a power conversion efficiency of 6.3% as compared to pristine CIS (5%) or CuS (3.5%). The possible reasons behind the high performance of the composite are elucidated using cyclic voltammetry (CV) measurements and electrochemical impedance spectroscopy (EIS).