| The field of electrochemical polymerization(EP) methods and films continues to attract great interest of many scientists due to their potential applications in the development and the construction of new advanced materials. In EP method, the monomers are electrochemically oxidized or reduced at the interface between electrolyte solution and electrode, and then the coupling reaction occurs among the radical monomers with deposition of the polymer film onto the electrode. In this method, the morphology, thickness and state of aggregation of the ED films can be easily modulated by controlling ED condition and get the ED films with rich structure and functional properties. Most importantly, ED can combine the synthesis and in situ deposition of polymer films in the target electrode in one step. Thus, ED techniques as a new way of preparing the film, provides a new way of film preparation for the polymers and small organic molecules which difficult for solution process.To most of the EP systems, it is very difficult to control the molecular weights of products and the structures of films, which fundamentally limited the fabrication of EP films with high qualities and controllable structures. Therefore, we are staring from the design concept of controllable ED films. First of all, design the monomer with determines coupling structure through choice of the electroactive group(such as carbazole, cyanopyridine); then, prepared the ED films with self-assembled nanostructures or nano-porous structure were using oxidation reduction electrochemical deposition, and further developed their applications. Based on these considerations, through the different way of electrochemical deposition, this paper carried out the following research:Firstly, discotic hexa-peri-hexabenzocoronene(HBC) molecules are synthesized by electrochemical cyclodehydrogenation reaction and in situ self-assembled to π-electronic, discrete nanofibular objects with an average diameter about 70 nm, which are deposited directly onto the electrode. The nanofibers consist of columnar arrays of the π-stacked HBC molecules and the intercolumnar distance is determined to be 1.19 nm by X-ray diffraction, which corresponds well to the distance of 1.1 nm observed by high-resolution transmitting electron microscopy. The diameter of the molecular columns matches the size of the discotic HBC molecule indicating face-to-face π-stacking of HBC units in the column. The HBC nanofibers on electrode are redox active, and the nanosized columnar structures provide a huge surface area, which is a great benefit for the charging/discharging process, delivering excellent capacitance of 155 F g-1. The described electrochemical deposition method shows great advantage for self-assembling the family of insoluble and structurally designable graphene-like nano materials, which constitutes an important step toward molecular electronics.Secondly, Supercapacitors(SCs), also known as electrochemical capacitors or ultracapacitors, are a type of energy storage device with advantages including a high power density relatively simple structure compared to batteries, long cycling life, and small size. Based on the redox-active polymer electrodes, the most optimal supercapacitor configuration is n/p type, i.e. the devices with an n-doped polymer as negative electrode and a p-doped one as positive(n/p-type supercapacitor). This type device has the advantages that all the doping charge is delivered during discharge at high potentials and both the electrodes are in the conducting(p- and n-doped) states. In this work, we demonstrate an effective strategy of designing high-performance n/p-type supercapacitor with ultrahigh volumetric capacitance based on POP film by electropolymerization. The film are unique at consist of perylene diimide(n-type) cores and dimeric carbazole(p-type) linkages which with rigid nanoporous structure. The design intent of separate n/p-doping is effectively increased the conductivity and stability at n-doped state. By virtue of these features, the thin-film delivers exacting supercapacitive performance, with a ultrahigh volumetric capacitance of 246 F cm-3(241.2 F g-1) at n-doped state and 153 F cm-3(210 A g-1) at p-doped state. The resultant all-solid-state n/p-type supercapacitive exhibited high energy density(22.07 mW h cm-3) and power density(17.4 W cm-3). The supercapacitor demonstrated excellent flexibility and good rate capability benefited from the highly crosslinked network skeleton and rich inherent nanopores that promote high-rate electron transfer and maintains its high performance, which is an important advance in flexible devices. The designed approach has the potential of being applied to the fabrication of other n/p-type supercapacitors.Thirdly, ion transport between polymer layers plays very important role in the electrochromic applications. To improve the ion transport properties, we report a novel poly(3,4-dioxythiophene) dimer(PM-BTE), synthesized by the electropolymerization of the diethoxy connected 3,4-dioxythiophene. The polymer was fully characterized by the different spectroscopic techniques. The PM-BTE soft network shows excellent electrochromic properties, such as the reversibility of oxidation and reduction, color switching from dark blue to brown yellow, optical contrast(?T=38.8%), coloration efficiency of 263.5 cm2 C-1 at 900 nm, low switching voltages and response time of 1.8 s, with an excellent stability and color persistence. The electrochromic performance shows improved properties when compared with the PEDOT(one-fold in coloration efficiency and 60% in response time). The better performance is attributed to the soft network of PM-BTE films which provided compatible ion transport channels.Finally, we developed a new type of layer by layer(LbL) self-assembled film preparation method by suing the molecular design and interface layer engineering. By cyanopyridine as electrochemical reductive coupling unit, we got the structure-controllable net-work film. Then, in suit one-pot rapid LbL assembly of polymeric films via alternation of reductive and oxidative electropolymerization has been demonstrated. This novel fabrication strategy for preparing multilayered films without moving or changing experimental gears would be a very powerful strategy to develop electrochemical methods applied in the preparation of self-assembled films. Given that both oxidative and reductive electropolymerization are well-established, this method is highly feasible for practical applications. Furthermore, the electroactive sites and functional units in monomers can be independent, which allows for a greater flexibility in molecular design and realization of functional LbL films for many organic and inorganic materials. |
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