Synthesis and Photovoltaic Performance of Ionic Dyes for Quasi-Solid State Dye-Sensitized Solar Cells

Abstract

We prepared the ionic dyes and investigated their electrochemical properties and photosensitizing performances in the quasi-solid state dye-sensitized solar cells (QS-DSSCs). The LUMO energy level of ionic dye with carbazole moiety is higher than that of the dyes with phenothiazine and triphenylamine chromophore, resulting in highest power conversion efficiency (PCE) in the QD-DSSC. Compared with Ru-complex sensitizer, the ionic dyes showed relatively low photovoltaic performance in the QS-DSSCs, originating in lower LUMO energy level. The effect of Li⁺ion in the quasi-solid state electrolyte on the photovoltaic characteristics of QS-DSSCs was investigated in order to confirm the correlation between the conduction band of TiO₂electrode and LUMO energy level of photosensitizers. The conduction band of TiO₂electrode could be reduced by adding the Li⁺ion in the electrolyte, attributing for the enlargement of PCE value in the QS-DSSC.

Keywords:

• Ionic dyes
• organic photosensitizers
• photovoltaic performances
• quasi-solid state dye-sensitized solar cells
• semi-solid state electrolyte

Acknowledgments

This research was supported by the 2010 Yeungnam University Research Grant and the Human Resources Development Program of the Korean Institute of Energy Technology Evaluation and Planning (KETEP) grant (No 20104010100580) funded by the Korean Ministry of Knowledge Economy.