Synthesize Of D-π-A Structure Dye And Its Application

The solar cells employing ruthenium polypyridyl complexes as charge-transfer sensitizers yield solar-to-electric power conversion efficiencies of over 11%under AM1.5 G sunlight,however,the ruthenium polypyridyl complexes can not be widely applied due to the disadvantages of high-cost and pollution.Pure organic dyes are promising for application in DSC in that they have much higher molar extinction coefficients and lower cost than those of ruthenium polypyridyl complexes,which are becoming more and more popular and chart a new direction for this research field henceforth.Referencing to the requirements of dyes in dye-sensitized solar cells and the latest tendency of development,we designed and synthesized three pure organic dyes with the D-π-A structure,coded C217,C218 and C219,respectively,through Suzuki Coupling, Vilsmeier-Haak reaction and Knoevenagel Condensation.The structure and performance of the three dyes were tested and characterized by UV-Vis,square-wave voltammetry and NMR, meanwhile,with the result showing that they have high molar extinction coefficients and suitable redox potentials.These dyes have achieved power-conversion efficiencies of 7.85%,9.08%,8.02%,respectively,under AM1.5 G sunlight on 2.6-μm-thick titania film.it has a low free energy of salvation due to its fused dithionothiophene,eliminating the dye-desorption during the long-term device operation.By comparing the UV-absorption spectra of C217,C218 and C219,we concluded that the introduction of electron donating group on the donor would make the absorption red-shift, while the long branches on the donor can improve the dissolvability of the dye,with little impact on the absorption.