Improvement of CdSe quantum dot sensitized solar cells by surface modification of Cu₂S nanocrystal counter electrodes

We report the improvement of a CdSe quantum-dot-sensitized solar cell (QDSSCs) based on surface modification of Cu₂S nanoparticle counter-electrodes (CEs). In this work, we explored a low-cost, easy method to fabricate counter electrodes by direct deposition of colloidal Cu₂S NCs on conducting FTO glass using drop casting or spin coating. The colloidal Cu₂S NC films provide high surface area, which improves the catalytic activity for the redox couple and enhances the final photovoltaic performance. A CdSe QDSSC based on the 0.1 M EDT treated Cu₂S CE/FTO shows a short-circuit current density (J_SC) of 7.95 mA cm^-2, a fill factor (FF) of 55.44%, and yielded a superior power conversion efficiency (η) of 2.1%, an improvement of 50% over that of the OA-capped Cu₂S CE/FTO CE (1.4%).