H3PW12O40/Co3O4–Cu2S as a low-cost counter electrode catalyst for quantum dot-sensitized solar cells

Abstract

This paper reports for the first time the preparation of Co₃O₄ nanorods by simple hydrothermal and annealing methods, which are doped with polyoxometalates that act as an intermediary in electronic transmission to accelerate electron transport. The designed H₃PW₁₂O₄₀(PW₁₂)/Co₃O₄–Cu₂S composite film was prepared by the screen printing method to boost its efficiency as the counter electrode for quantum dot-sensitized solar cells, where the preparation process is simple and inexpensive. PW₁₂/Co₃O₄–Cu₂S (J_sc = 16.60 mA cm⁻², V_oc = 0.636 V, R_ct = 0.32 Ω and FF = 0.436) shows better electrocatalytic performance compared to the original Co₃O₄ and Cu₂S. Accordingly, the photoelectric conversion efficiency of PW₁₂/Co₃O₄–Cu₂S is 4.67%, which is 10%, 46%, 55.6%, and 72% higher than those of Co₃O₄–Cu₂S (4.2%), Cu₂S (2.54%), PW₁₂/Co₃O₄ (2.07%), and Co₃O₄ (1.30%), respectively. Electrochemical impedance spectroscopy and Tafel measurements performed on two CE symmetric virtual cells proved the excellent electrocatalytic activity of PW₁₂/Co₃O₄–Cu₂S. Therefore, this composite film can be used as an alternative option for QDSSC counter electrodes.