Acid@base co-sensitization strategy for highly efficient dye-sensitized solar cells

Abstract

Two new base dyes bearing pyridyl acceptor ( Py-1 and Py-2 ) are synthesized, which are respectively co-sensitized with an acid dye containing cyanoacetic acceptor ( NP-1 ), constructing the acid@base co-sensitized solar cells (co-DSSCs). The lightspot is that the carboxylic and pyridyl groups could anchor onto the Brønsted-acid and Lewis-acid sites of TiO 2 surfaces, respectively. The research results show that the combination of these acid and base dyes is beneficial to suppress the competitive adsorption between dyes, thus increasing the dye coverage on TiO 2 surfaces and decreasing the electron recombination, and further raising the photovoltage; moreover, their complementary spectral responses can significantly increase the photocurrent. Therefore, the acid@base co-DSSC based on NP-1@Py-2 (2:3) delivers the best photovoltaic performances in comparison to the DSSC based on NP-1 , in which the photovoltaic efficiency is increased by 32.5% (from 4.0% to 5.3%). Furthermore, the photovoltaic performances under different irradiation and long-term stability measurements can provide a basis for application evaluation of co-DSSCs. • Synthesize two different π-bridge pyridyl dyes. • Explore a new acid@base co-sensitization system. • Compare the effect of co-sensitized ratios on photovoltaic-device efficiency. • Improve the light-harvesting ability through spectral complementary absorption.