High Performance Organic Dyes with Electron-Deficient Quinoxalinoid Heterocycles for Dye-Sensitized Solar Cells under One Sun and Indoor Light.

Abstract

A series of Y shaped D-A-π-A sensitizers incorporating quinoxaline or quinoxalinoid moieties (MM-1~MM-6) were prepared and applied onto dye-sensitized solar cells (DSSCs). By the introduction of quinoxaline or quinoxalinoid functionalities, the absorption extinction coefficient can be enhanced. Stepwise modifications on the structures were done by converting the alkyl chains to alkoxy chains and by incorporating electron donating moieties on different positions. The new dyes MM-5 and MM-6 were found to perform remarkable efficiency in light-harvesting either under sunlight or under indoor light. Through co-sensitization of MM-3 and MM-6, the DSSCs exhibited a PEC of 7.92% under one sun (AM 1.5G) illumination, and 27.76%, 28.74% and 30.45%, respectively, under 600 lux, 1000 lux and 2500 lux indoor light using a TL84 fluorescent lamp. The high performance that was achieved by mixing MM-3 and MM-6 can be partly ascribed by a better dye-coverage on the TiO2 surface.