Synthesis And Properties Of Novel Linear Sensitizers Of Dye-Sensitized Solar Cells Based On Perylene Diimide

Perylene tetracarboxylic acid diimide (PDI) derivatives are important molecular building blocks of organic molecular materials in the field of organic field effect transisitors, light-harvesting system of solar cell, photovoltaic devices, light emitting diodes, and robust organic dyes that are resistant to photobleaching. Because PDIs have low light and thermal fading rates, high luminescence efficiency, wide absorption and emission bands in visible region, and special optoelectronic properties, the researches on PDI compounds become the focus of many research groups around the world in recent years.Driven by the demands of diverse applications, the modification on molecular structure of PDI aimed at changing the photophysical properties has attracted a lot of research interest in the past decade. To create a new PDI dye with outstanding photophysical and photochemical properties, the combination of PDI and multifunctional groups in one molecule is a rational design, we described here the synthesis and properties of a series of novel PDIs which have never been reported in literature. The content of this thesis includes:Chapter1:An overview of the basic properties of PDI and its derivatives is presented in this chapter. Meaning while, a detailed review on the development of linear PDIs and the application of PDIs in dye sensitized solar cell (DSSC) is also include in this chapter.Chapter2:A series of linear perylenetetracarboxylic imide derivatives (PDIs), abbreviated as PN, PO-PN and PO-PO-PN, with high molar extinction coefficients and broad absorptions in visible to near-infrared (NIR) region are preppared. These new dyes are designed for the use as sensitizers in dye sensitized solar cell (DSSC) with a motive to enhance the optical absorption of mesoporous titania film and light collecting efficiency. Energy transfer from PO parts to PN unit is revealed by absorption and fluorescence spectra. The energy transfer efficiencies estimated from the fluorescence quenching efficiencies are almost100%. The IPCE spectra revealed distinctively the contribution of PO parts to the solar energy conversion, which suggests that the intramolecular singlet-singlet energy transfer is a reliable strategy to improve the light absorbing abilities of a dye adsorbed on titania films. The necessary efforts to further improve the efficiency of cells by the molecular design of PDI derivatives are discussed.Chapter3:We have successfully synthesized a series rigid and linear PDI-based donor-acceptor oligomers linked together by phenyl units, abbreviated as PO-PN PO-PO-PN and PO-PO-PO-PN and the reference molecules, along with their structure characterization.Chapter4:The photophysical properties of these series of newly prepared compound were investigated by the steady state electronic absorption, fluorescence spectra. In these compouds, when the PO units was electively excited, photoinduced intramolecular energy transfer proceeded efficiently from the excited PO units to the PN unit, and had an efficiency as high as99%. Forster type energy transfer process like energy hopping among the chromophores are investigated. All of these energy transfer rate constants and efficiencies could be estimated using the photophysical data of the compounds. When excited at630nm where is almost the absorption of PN, the electron transfer efficiency gradually increases in PO-PN, PO-PO-PN, PO-PO-PO-PN. Moreover, the electron transfer efficiencies of the three compounds increase significantly in the polar solvent.