Quasi-solid-state composite electrolytes with Al2O3 and ZnO nanofillers for dye-sensitized solar cells

Abstract

In the literature, so far, in-situ chemical cross-linking methods have been utilized for the preparation of Al2O3 or ZnO-composite polymer gel electrolytes (PGEs). Such PGEs have shown poor performance in quasi-solid-state dye-sensitized solar cells (QS-DSSCs) under one-sun conditions. Moreover, the QS-DSSCs using ZnO-PGEs had higher open-circuit voltages (Voc) than the cell using Al2O3-PGEs; but their conversion efficiencies are much lower. To solve this problem, for the first time, composite printable electrolytes (CPEs) are fabricated by dispersion Al2O3 and ZnO nanofillers (NFs) in the quasi-solid-state electrolytes. The electrochemical properties of the CPEs and their effects on the QS-DSSCs performance are systematically studied and compared. The results show that the diffusion coefficients of ions in Al2O3CPEs are much higher than in ZnOCPEs. However, the introduction of ZnO NFs significantly decreases the charge recombination at the photoelectrode/electrolyte interface than do by the Al2O3. Therefore, the QS-DSSCs using Al2O3CPE and ZnOCPE have, respectively, higher current density and higher Voc; and the highest efficiencies achieved are 8.73% and 7.59%. These efficiencies are significantly higher than those reported for the QS-DSSC PGEs using the two NFs. The mechanisms of the two NFs are proposed by analysis the iodide ions on the two NFs using X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy.