The low-cost g-C3N4/CuS electrode for QDSCs prepared with low-temperature solid-state method

Abstract

The graphene-like carbon nitride (graphitic C3N4, g-C3N4) and CuS composite materials were prepared via a facile low-temperature solid-state method as the eco-friendly and low-cost counter electrodes (CEs) for quantum dot sensitized solar cells (QDSCs). Compared with the former complex processing, low-temperature solid-state method is simple and easy towards mass production. Based on XRD, SEM, EDX and TEM results, it was confirmed that g-C3N4 constructed a transport network for electron transfer, while distributed CuS played a catalytic role to contact with polysulfide electrolyte in reduction reaction at CE/electrolyte interface. Electrochemical Impedance Spectroscopy, Mott-Schottky and CyclicVoltammetry tests were performed for the electrochemical properties of composite counter electrodes with various C3N4/CuS ratio. The CE sample (CN/10CuS) with appropriate ratio possessed lower interface impedance, more catalytic active sites and better stability, and power conversion efficiency (PCE) of QDSCs with CN/10CuS CEs reached 5.05% under one sun, which is comparable to g-C3N4/CuS CE prepared with other routes in the same conditions.