Highly efficient, stable and reproducible CdSe-sensitized solar cells using copper sulfide as counter electrodes

A mixture composed of CuS and Cu1.8S has been easily fabricated via a solvothermal method followed by screen-printing to form a counter electrode. A highly reproducible record efficiency of 6.28% for the assembled CdSe-sensitized solar cells has been achieved, and the irradiation, as well as conservation stability, have also been greatly improved compared to the brass foil based solar cells. With different size and morphology, the phase of CuS shows a slightly superior performance than Cu1.8S through investigating the influence of S/Cu ratio on the efficiency. The sintering temperature of the counter electrode film has also been studied, and the results show that 400 degrees C is favorable for good conductivity, high electrochemical activity, low charge transfer resistance in a solid-solid interface and between the catalysts and electrolyte. Because of the low cost, convenient fabrication, easy of sealing, as well as the high efficiency, reproducibility and excellent stability of the devices, the as-prepared copper sulfide could be potentially and extensively utilized in semiconductor-sensitized solar cells.