Synthesis And Photoelectric Properties Of Pyrene - Like Small Molecules And A2B2 Porphyrin Sensitizing Dyes

In this paper, the main work were synthesized and characterized several dyes, we designed two small molecule dyes which were taked fluorene as the electron donor, while thiophene and furan as the π bridge; Three A2B2 type porphyrin dyes were obtained by different length of alkyl chain aromatic amines as the electron donor.Then these dyes were introduced to DSSCs as sensitizers to characterize the electrochemical and photovoltaic properties.Thiophene and furan at the 9th position of the fluorene were prepared through condensation reaction as the starting materials, followed with formylation on 2th position of thiophene and furan, then the Knoevenagel condensation of intermediate and acrylic acid gave two simple structure dyes F-S and F-O, which were consisted of flourene as the electron donor, while thiophene and furan as the π bridge. All the intermediates and target dyes were characterized by 1HNMR. After testing the optical properties found that only a single atom change lead to a greatly difference about the two dyes. The maximum absorption wavelengths of UV-vis of dye F-O was 20 nm red shift compared to F-S. The batteries were also assembled and tested, the photoelectric conversion efficiency of F-O was 2.76%, while the efficiency of F-S was just 1.98%. The results illustrated that the introduction of appropriate π bridge structure can significantly improve the photovoltaic properties of fluorene dyes.Three new A2B2 type porphyrin which taked different length of alkyl chain aromatic amines as the electron donor were obtained, we via MacDonald method taked N,N- dimethyl (butyl, octyl) benzaldehyde and 4-carboxybenzaldehyde together and then using Zn(OAc)2·2H2O and base hydrolysis afforded three dyes. The UV-Vis spectra and emission spectra of the three dyes were similar due to their analogous molecular structure in which just intruduced different prevent aggregation alkyl chain. The sensitizer with a butyl chain DA-4 achieved a higher photoelectric conversion efficiency(PCE) than that with a octyl chain DA-8 (η is 2.02% and 1.89%) because of DA-4 had an appropriate alkyl chain length, performed the lower steric hindrance and higher adsorption. Futhermore, the sensitizer with a methyl performed the lowest PCE(η=1.10%) due to its fastest charge recombination rate and slowest electron injection which greatly reducing the PCE, so the length of alkyl chain on electron donor take an important role in PCE of DSSCs.