Highly efficient and stable spray assisted nanostructured Cu2S/Carbon paper counter electrode for quantum dots sensitized solar cells

Abstract

The counter electrode (CE) plays a significant role in determining the overall performance and long-term stability of quantum dots (QDs) sensitized solar cells (QDSCs) by collecting the electrons from the external circuit and catalyzing the regeneration of the oxidized electrolyte. In this work, we report a simple, low cost and large area scalable spray deposition approach to fabricate nanostructured Cu2S CE on a carbon fiber paper (CP). The QDSCs were assembled with optimized spray assisted nanostructured Cu2S/CP CEs, and yield a photoconversion efficiency (PCE) of 5.06%, which is 28% higher than QDSCs based on Cu2S/Brass CEs. The PCE can be further boosted to 5.89% upon optimization of the photoanode structure. In addition, QDSCs with Cu2S/CP CEs exhibit better long-term stability than QDSCs with Cu2S/Brass CE. This excellent performance and satisfactory long-term stability of QDSCs with Cu2S/CP CEs is mainly attributed to the synergistic effect of excellent conductivity of CP and high and stable catalytic activity of nanostructured Cu2S, which is confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. Thus, our results define a cost-effective and large area scalable approach to fabricate highly efficient and stable CEs, which is an important step toward the fabrication of solar driven optoelectronic devices.