Synthesis And Properties Of Quinoxaline Organic Dyes With Spiro Structure Auxiliary Units

Dye-sensitized solar cells have good development prospects due to their low manufacturing cost and low environmental problems.A series of triphenylamine organic sensitizing dyes were synthesized by modifying different triphenylamine structural units by introducing different groups(styrene and quinoxaline units).Another series of new D-A-?-A organic dyes were designed and synthesized by introducing quinoxaline units as auxiliary acceptors and changing electron donors.The six dyes were characterized by means of nuclear magnetic resonance and mass spectrometry.The electrochemical and photophysical properties of the dyes and the photovoltaic properties of DSSCs based on these dyes were studied.It is found that in the triphenylamine organic dye,compared with the dye FWD10,the absorption structure of the dye FWD9 is red-shifted due to the extension of the conjugated structure of the dye FWD9.The absorption spectrum of dye FHD7 is blue-shifted,but there is a very weak shoulder at the absorption peak,which makes the absorption intensity of dye FHD7 red-shift to a certain extent,but its molar absorptivity is not improved,still equivalent to half of the dye FWD10 molar absorption coefficient.Among the quinoxaline-based organic dyes,the dyes FHD4-1 and FHD4-2 are significantly red-shifted,and the absorption spectra of the two dyes are wider than the dye FHD4-3.This indicates that the triphenylamine derivative(2-ethylhexyloxy)and the N,N-dialkylaniline are more favorable for broadening the absorption range.Through the test of photovoltaic performance,the conversion efficiencies of DSSCs based on these three dyes were 2.90%?3.52%?3.20% without adding CDCA.Since the hydrophobic alkyl chains attached to the conjugated-? bridge of the three dyes can prevent charge recombination and are beneficial for inhibiting aggregation between dye molecules,the dyes are reduced based on the dye loading after the addition of CDCA.The conversion efficiency of DSSCs has been reduced,respectively 2.2.29% ? 2.56% ? 1.83%.In the quinoxaline-based organic dyes,the conversion efficiencies of the DSSCs based on these three dyes are 3.45%?3.59%?3.90%,respectively,without adding CDCA.Since the long alkyl chain introduced in the dyes FHD4-1 and FHD4-2 prolongs the distance between molecules,it is loosely adsorbed on the surface of Ti O2,resulting in severe electron recombination.Therefore,after the addition of the co-adsorbent,the co-adsorbent can Tightly adsorbed on the surface of Ti O2,the electron recombination rate is reduced,and the current short-circuit density of the two dyes is increased,and the power conversion efficiency is 3.75%?4.39%?3.61% respectively.