Synthesis of Cross-linked Thin Films Containing Fullerene Units and Their Performance of Supercapacitor

A series of C-60 derivatives functionalized by carbazole group with great electrochemical activity were designed and synthesized via Bingel reaction. Three monomers (2Cz-C-60, 4Cz-C-60, 6Cz-C-60) were finally obtained with different molar ratios between C-60 and malonate used in Bingel reaction. The molecular structure of these monomers were fully characterized by proton nuclear magnetic resonance spectra, Matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), Fourier transform infrared spectroscopy (FTIR), and UV-Vis absorption. Electrochemical polymerization of these monomers were processed to form linear or cross-linked organic conducting polymer films, denoted as Poly[2Cz-C-60], Poly[4Cz-C-60] and Poly[6Cz-C-60], which were attributed to the coupling of electrochemical activity group of N-alkyl carbazole. Their electrochemical polymerization was processed under three-electrode system of the electrochemical workstation (ITO or glassy carbon as working electrode, titanium plate or Pt wire as counter electrode and Ag/Ag+ as reference electrode). The chemical structures of the polymers obtained were clearly dependent on the definite electrochemical condition such as potential, electrolyte, concentration and scan rate during the polymerization. The thickness of the films obtained by the electrochemical polymerization could be controlled precisely by controlling the cycles of cyclic voltammetry (CV). The electrochemical polymerization of the polymers had the same features of instantaneous nucleation and layered growth concluded by the atomic force microscope images of the films under different CV cycles. Finally, the films show globular stacking features. After CV test, the bipolar characters (N-alkyl carbazole group as the p-doping and C-60 group as the n-doping), fast and reversible redox properties of the organic conducting polymers films have been found. Then we explored the charge storage ability of the polymers as the electrode materials, which possessed considerable development potential to some extent.