Effect of Extending the Conjugation of Dye Molecules on the Efficiency and Stability of Dye-Sensitized Solar Cells

Abstract

We designed and synthesized two organic dyes (<b>A6</b> and <b>A10</b>) for dye-sensitized solar cells (DSSCs) by extending the molecular conjugation strategy. The sensitizer <b>A10</b> was constructed by inserting ethene into our previously reported sensitizer <b>AZ6</b>. The sensitizer <b>A6</b> was obtained by further substituting the hydrogen of ethene with another donor (D) and π-bridge-acceptor (π-A) segment. The UV-vis spectra and <i>J-V</i> curves showed that the dyes <b>A10</b> and <b>A6</b> could effectively facilitate the light-harvesting and photocurrent densities with respect to <b>AZ6</b>. Consequently, the <b>A10</b>-based DSSC achieved an enhanced efficiency (8.54%) with a high photocurrent (18.81 mA cm^-2). Desorption experiments of dyes adsorbed on TiO₂ showed that compared with the monoanchoring dyes <b>AZ6</b> and <b>A10</b>, the dianchoring configuration effectively strengthened the affinity of dye <b>A6</b> with the photoanode, making it more difficult to leach from the photoanode. The <b>A6-</b>based DSSC shows outstanding stability, and its overall efficiency could remain 98.0% of its initial value after 3000 h of aging time, exceeding that of its monoanalogue <b>AZ6</b> (remained 78.3% after 3000 h).