The effect of CuS counter electrodes for the CdS/CdSe quantum dot co-sensitized solar cells based on zinc titanium mixed metal oxides

The highly catalytic copper sulfide (CuS) thin films were designed and combined with the FTO substrates by the chemical bath deposition method and were used as counter electrodes (CEs) for the CdS/CdSe quantum dot-sensitized solar cells (QDSSCs) based on zinc titanium mixed metal oxides (MMOs) deriving from the layered double hydroxide precursor for the first time. Formation of CuS films was confirmed by X-ray diffraction and X-ray photon spectroscopy. The surface morphology of CuS films was observed by scanning electron microscopy (SEM). Systemic electrochemical test was used to investigate the catalytic performance of CuS films and the photovoltaic performance of QDSSCs. When the number of deposition cycles (30 min per cycle) was two, the CuS CEs of excellent performance were obtained. The CuS CEs exhibited higher performance for QDSSCs based on ZnTi MMOs than the conventional platinum (Pt) CEs. The best power conversion efficiency of CdS/CdSe QDSSCs using optimal CuS CEs reached 3.95%, which is more than twice higher than that of Pt CEs.