Preparation Of Conductive Polymer Inverse Opals And Their Application In Dye-sensitized Solar Cell

Conductive polymer inverse opals(IOs), with an ordered interconnected pore structure, having good electrical conductivity and a large specific surface area, have been widely used in the field of sensors, solar cells and catalysis. Currently, the conductive polymer IOs are mostly prepared by electrochemical depositon method. The complex deposition process could easily lead to excessive polymerization and is difficult to controls. This thesis proposes an air-water interface oxidation polymerization method to fabricate conductive polymer IOs, and further employs them as a replacement for the expensive Pt counter electrodes in Dye-Sensitized Solar Cell(DSSC).(1) By using polystyrene(PS) colloidal crystals(CCs) as template, polypyrrole(PPy) and polyaniline(PANI) inverse opals were fabricated through an air-water interface oxidation polymerization method. Addition of ethanol into the water phase promote the infiltration of water into the CCs. ATR-FTIR, SEM、UV-vis-NIR、CA were employed to characterize the structure, morphology and the optical structures of the samples. It was found that the addition of ethanol promotes the infiltration of solution into the voids of CCs. With addition of 4%v/v ethanol, the conducting polymer monomer solution fully infiltrate the CCs and the layer number of pores is equal to that of the spheres in CCs. The surface of IOs is not covered with conducting polymer and have open pores. After 24 hours of polymerization, IOs with good mechanical strength could be obtained. This method could be applied to the fabrication of IOs with different layers and also PANI IOs.(2) To enhance the conductivity of the IOs, various organic and inorganic acids were used to dope the PPy IOs, which were used as counter electrodes in DSSC. The influence of doping on the photoelectric conversion efficiency(PCE) of DSSC were studied. FTIR, SEM, UV-vis-NIR, TG, C-V analysis were employed to characterize the morphology, thermal stability and catalytic properties of the doped IOs. IV and EIS impedance spectra were used to study PCE of DSSC. The results showed that the dopant species affect the formation of structure. Small anions could dope the CCs at high concentration, while large anionic surfactant-type dopant could only dope at low concentration. Otherwise, the CCs were broken during the process. Additionally, the thermal stabilities of PPy IOs were affected by the dopants. Sodium dodecyl sulfate depress the thermal stability of IOs. Hydrochloric acid or p-toluenesulfonic acid, by contrast, enhances the thermal stability. It was also found that p-toluenesulfonic acid doped IOs improves PCE of DSSC and sodium dodecyl sulfate enlarges the diffusion resistance of electrolyte and reduced PCE of DSSC. Doped PPy IOs have good catalytic performance for I-/I3- redox couple, and provide a performance comparable to that of Pt electrode.