Impact of π-spacers of dithieno[3,2-f:2′,3′-h]quinoxaline-based organic dyes with three π-spacers on the solar cell performance

Three novel dithieno[3,2- f :2′,3′- h ]quinoxaline-based organic dyes ( IQ-C, IQ-D and IQ-F ) with three π-spacers were synthesized and developed for dye sensitized solar cells, where dithieno[3,2- f :2′,3′- h ]quinoxaline was used as electron-withdrawing π-spacers, and 2,3-diphenylquinoxaline or dibenzo[ a,c ]phenazine as auxiliary electron-withdrawing π-spacers. The dye IQ-D with 2,3-diphenylquinoxaline as auxiliary electron-withdrawing π-spacer exhibited higher photocurrent ( J sc ) and photovoltage ( V oc ) than that of the dye IQ-C with 2,3-bis(4-(octyloxy)phenyl)quinoxaline as the additional electron-withdrawing π-spacer, due to the larger adsorption amount of IQ-D . The dye IQ-F with a rigid conjugated dibenzo[ a,c ]phenazine as additional electron-withdrawing π-spacer showed the highest efficiency of 6.54% under AM 1.5 G irradiation. It was demonstrated that the π-spacers influence the photovoltaic performance of the dithieno[3,2- f :2′,3′- h ]quinoxaline-based organic dyes significantly. The results indicated that the dyes with three π-spacers are promising candidates for efficient dye-sensitized solar cells.