The TiO₂ films with sandwich-type polyoxometalates in dye sensitized solar cells with electron recombination decreasing and dye adsorption increasing

Abstract

Unfavorable electron recombination, which hinders the efficiency of dye-sensitized solar cells (DSSCs), usually occurs at the TiO₂/dye/electrolyte interface on a photoanode. Polyoxometalates (POMs), as good electron acceptors, can be used as electron-transfer materials in DSSCs to improve electron transport in TiO₂ and reduce electron recombining on the interface of a photoanode. In this paper, the pure inorganic sandwich-type POM Na₉[Na₃(H₂O)₆Cu₃(H₂O)₃(SbW₉O₃₃)₂]·40H₂O (Cu₃Na₃POM) was mixed with TiO₂ to form nanocomposites by simple sol-gel method. X-ray photoelectron spectroscopy (XPS) proved that Cu₃Na₃POM and TiO₂ combined. Then the nanocomposite was doped with P25 to form Cu₃Na₃POM@TiO₂/P25 photoanodes which were applied to the DSSCs. The Cu₃Na₃POM improved the transfer and recombination of electrons in the photoanode, proved by open circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) and ultraviolet-visible (UV-vis) absorption spectra showed that Cu₃Na₃POM optimized the morphology of the photoanode and the adsorption capacity of dye. The electrochemical test showed that the photoelectric conversion efficiency of DSSCs with Cu₃Na₃POM@TiO₂/P25 photoanodes was enhanced to 6.91%, which was 13.66% higher than the DSSCs without Cu₃Na₃POM.

Graphical Abstract

Keywords:

• Dye-sensitized solar cells
• polyoxometalate
• electronic transmission
• dye adsorption
• photovoltaic performance
• photoanodes

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Natural Science Foundation of Jilin Province (No. 20200201440JC) and the Horizontal Research Project of Jilin University (No. 3R218AD53430).