Molecular design of organic dyes based on vinylene hexylthiophene bridge for dye-sensitized solar cells

Abstract

Three donor-(π-spacer)-acceptor (D-π-A) organic dyes, containing different groups (triphenylamine, di(p-tolyl)phenylamine, and 9-octylcarbazole moieties) as electron donors, were designed and synthesized. Nanocrystalline TiO2 dye-sensitized solar cells were fabricated by using these dyes. It was found that the variation of electron donors in the D-π-A dyes played an important role in modifying and tuning photophysical properties of organic dyes. Under standard global AM 1.5 solar condition, the DSSC based on the dye D2 showed the best photovoltaic performance: a short-circuit photocurrent density (Jsc) of 13.93 mA/cm2, an open-circuit photovoltage (Voc) of 0.71 V, and a fill factor (FF) of 0.679, corresponding to solar-to-electric power conversion efficiency (η) of 6.72%.