Design And Synthesis Of Aromatic Amine Dyes For Dye-Sensitized Solar Cells

The traditional energy, such as coal, oil, and natural gas, will be consumed completely in near future. Meanwhile, as the traditional energy is excessively used, the environmental problem becomes more and more serious, and extreme climate phenomenon happens frequently. Therefore, it's imminent to develop and utilize new energy. Solar energy attracts a lot of concern due to its cleanness and not subject to regional restriction. Among many ways of utilizing of solar energy, dye-sensitized solar cells (DSCs) attract many researchers' interest, because of its low cost and simple fabricating process. Photosensitive dye is the core of DSCs, which is one of the decisive factors on photoelectric conversion efficiency. When the photosensitive dye captures a photon, the dye molecule is in the excited state. The dye in the excited state will change to oxidation state by injecting one electron to the conductive band of the semiconductor. Then, the dye in oxidation state can obtain an electron from the electrolyte rapidly, and return back to ground state, completing a cycle. Because the molecular structures of organic dyes are in diverse form and can be easily designed and synthesized, organic dyes gradually become alternatives of noble metal photosensitizers, and now it's a research focus.Based on the above background, in this paper,8 novel organic dyes have been designed and synthesized. Adopting mass spectra (MS) and proton nuclear magnetic resonance (1HNMR) technology, the structures of these dyes have been characterized. We also studied the photophysical and electrochemical properties of these dyes and their performance of DSCs. In order to get a further understanding of the prosperities of these dyes, their structures were calculated under density functional theory calculation.Donor-Ï€-acceptor (D-Ï€-A) structure is the classic designed structure of organic photosensitizer. In this paper, in order to extend the adsorption of the organic dye, we expanded the classic structure, to design a novel D-Ï€-A-A structure by introducing an additional acceptor. Besides, a kind of acenaphthopyrazine dyes were designed and synthesized. We mainly discussed the difference of their ability to supply electron between diphenylamine and triphenylamine when they served as electron donor.The results show that owing to the twist between the original conjugated structure and the newly introduced group, the conjugated system hasn't got extended. The DSCs base on this type of organic dye has low efficiency. But, the efficiency of these dyes becomes higher as the electron-withdrawing ability of the introduced acceptors becomes stronger. This result shows that the designing concept, D-Ï€-A-A structure is feasible, which can reduce the formation of dark current. Though, triphenylamine has an additional benzene ring, and extend the conjugated system, the electron can't be transferred easily due to the twist of the molecule by the large triphenylamine group, and its ability to supply electron is lower than biphenylamine. The structure of the dye was calculated under density functional theory calculation, which proved that the intramolecular charge separation can be achieved after stimulating.