The Synthesis And The Study Of Properties Of Low-bandgap Donor-acceptor Conjugated Polymer

The study of this paper is focusing on the design synthesis of newpolymer which is applied as active photovoltaic material in organic solarcell. The alternating copolymers incorporating diformyltriphenylamineand diformylcarbazole which have been synthesized via Vilsmeier-Haackreaction and p-phenylenediamine monomer have been synthesized viaschiff-base reaction. The donor-acceptor type organic photovoltaicconjugated polymers consisting of the alternating copolymers as the donor,with the perylene-bisimide derivative unit as the acceptor, which feature thestructures of A-π-D-π-A, have been synthesized by high-temperaturesolution polycondensation. The structures of conjugated polymers arecharacterized by means FTIR, nuclear magnetic resonance (1H NMR), gelpermeation chromatography (GPC). The thermal properties of the polymersare studied by differential scanning calorimetry (DSC),thermogravimetry(TG). The photophysical, electrochemical properties of the polymers are investigated by UV-vis absorption spectra(UV),fluorescence-emission spectra(FE) and cyclic voltammetry (CV).Meanwhile, the morphology of the donor-acceptor type conjugatedpolymers which are in the atmosphere of different solvents with differenttime is studied by Atomic Force Microscope(AFM).The test results show that these polymers have band gaps of1.3-1.7eV,so we obtain the donor-acceptor type conjugated polymers with lowband-gap. The data of Tg show that the polymers have good thermalproperties, because their decomposition temperature are both greater than400oC at the5%mass loss, which is very important to the life and stabilityof organic optoelectronic devices. UV absorption spectroscopy show thatthe double bond between two aromatic rings broadened the absorption bandof the polymers because of its electron-donating property, enabling moreefficient harvesting of photons from the solar spectrum. Furthermore, thedouble bond between two aromatic rings of the polymers leads to a highlyordered structure, which is essential for high charge-carrier mobility. AFMimages show that the thin films of the donor-acceptor type conjugatedpolymers can form obvious and ordered phase separation after being in theatmosphere of dichloromethane with some time. This will be in favor ofimproving the power conversion efficiency of the polymer solar cells.Moreover, the donor-acceptor type conjugated polymer can also be used asa compatibilizer for polymer solar cells to improve compatibility and the photoelectric properties.