Copper sulfide/ cuprous selenide as a new counter electrode for quantum-dot-sensitized solar cells

摘要： In this paper, the copper sulfide/copper selenide (Cu2S/Cu2Se) composite is presented as a new counter electrode (CE) in the quantum-dot-sensitized solar cells (QDSSCs), for the first time. This novel CE shows a higher electrocatalytic performance towards the polysulfide electrolyte. The obtained results show that, with the change of the CE material from the CuS to the (Cu2S/Cu2Se) composite, the short-circuit current and the cell efficiency are increased from 7.22 to 19.18 mA/cm2 and 1.36 to 4.60%, respectively. The electrochemical impedance spectroscopy (EIS) study and the Tafel polarization analysis demonstrate that the (Cu2S/Cu2Se) CE shows a lower charge transfer resistance in the electrolyte–CE interface, 6.2 ? for the (Cu2S/Cu2Se (5)) CE, in comparison with the pure Cu2S CE, 142.1 ?.