Influence of the terminal electron donor in D-D-π-A phenothiazine dyes for dye-sensitized solar cells

We report three new molecularly engineered push-pull dyes based on phenothiazine (PTZ) as a pi-conjugating linker and arylamine moiety as donor and compared with a simple phenothiazine derived reference dye. Absorption spectra, electrochemical cyclic voltammetry, theoretical calculations, current -voltage curves and electrochemical impedance spectroscopy were performed to understand the terminal electron donor influence on the performance of D-D-pi-A PTZ dyes. Among these four dyes, the dye incorporating a 9-hexyl-9H-carbazole shows the best photovoltaic performance: a short-circuit photocurrent density of 14.02 mA cm(-2), an open-circuit photovoltage of 748 mV, and a fill factor of 0.68, corresponding to an overall conversion efficiency of 7.13% under standard global AM 1.5 solar light conditions. (C) 2014 Elsevier Ltd. All rights reserved.