Trilateral π-conjugation extensions of phenothiazine-based dyes enhance the photovoltaic performance of the dye-sensitized solar cells

Abstract

Two novel organic dyes TLEP-1 and TLEP-2 based on phenothiazine with trilateral π-conjugation extensions were designed and synthesized for dye-sensitized solar cells, where phenothiazine ring was linked with two phenyl moieties at 7- and 10-positions as the first and second π-conjugation extensions, and with furan or thiophene ring at 3-position as the third π-conjugation extension for TLEP-1 and TLEP-2, respectively. The influence of the π-conjugation extensions on the photovoltaic performance was evaluated. The cell based on TLEP-2 exhibits an impressive short-circuit photocurrent density of 14.87 mA cm−2, which is much higher than the cell based on the reference dye without π-conjugation extension (9.01 mA cm−2), leading to high power conversion efficiency of 7.33% under simulated AM 1.5 G illumination condition. The results indicate that the trilateral π-conjugation extensions are an effective way to improve the photovoltaic performance of the dye-sensitized solar cells.