Antimony tin oxide/lead selenide composite as efficient counter electrode material for quantum dot-sensitized solar cells

Antimony tin oxide (ATO)/lead selenide (PbSe) composite was rationally designed and fabricated on fluorine doped tin oxide glass (FTO) for using as counter electrode (CE) of quantum dot sensitized solar cells (QDSSCs). The electrocatalytic activity of the CE is deeply investigated in the polysulfide electrolyte by employing the Tafel, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) of the symmetrical cells. The results confirm that the ATO/PbSe CE has better electrocatalytic activity and stability than that of PbSe CE obtained by pulse voltage electrodeposition (PVD). The enhanced electrocatalytic performance of ATO/PbSe CE can be attributed to its high specific surface area, excellent permeability, conductivity and interface connectivity, which provide more electrocatalytic active sites for the reduction of polysulfide species, as well as fast channels for ions diffusion and electron transport. As a result, the CdS QDSSCs and CdS/CdSe co-sensitized QDSSCs assembled by the ATO/PbSe CE exhibits better power conversion efficiency (g) of 1.72% and 5.59%, respectively than that of PbSe CE obtained by PVD. Furthermore, photovoltaic property of the ATO/PbSe CE in CdS/CdSe co-sensitized QDSSCs keeps stable for over 200 min. This present work provides a simple and effective strategy for the construction of high-performance CE materials of QDSSCs.

Automated summary

In this study, ATO/PbSe composite was designed as the counter electrode for QDSSCs, showing enhanced electrocatalytic activity and stability compared to PbSe CE obtained by PVD. The improved performance is attributed to the high specific surface area, permeability, conductivity, and interface connectivity of ATO/PbSe CE, providing more active sites for reduction and fast channels for ion diffusion and electron transport. As a result, the CdS QDSSCs and CdS/CdSe co-sensitized QDSSCs assembled with ATO/PbSe CE exhibited higher power conversion efficiency than PbSe CE obtained by PVD, with stable photovoltaic properties over 200 minutes.