Self‐Assembly and Crystalline Growth of Poly(3,4‐ethylenedioxythiophene) Nanofilms

Abstract

Organic polymers possessing a conjugated p-electron system have fascinated scientists all over the world because of their electronic and physical properties. These nanostructured polymers have received great attention because of their potential application in electronic displays, electrode materials in batteries, semiconductors, sensors, capacitors, molecular electronic circuit elements, and secondary batteries. [1][2][3][4][5] Optoelectronic devices often require polymeric transparent electrodes to improve their performance and to create devices with only polymer components. [6][7][8][9] Poly(3,4-ethylenedioxythiophene) (PEDOT) can be a good material for optoelectronic devices because of its high conductivity, narrow band gap, good stability at ambient conditions, and film-forming properties. For applications requiring both conductivity and good optical/electrical properties, it can be blended with tougher insulating polymer matrices, resulting in mechanically resistant and easy-to-process conducting polymer blends. [10,11] In these blends, conductivity is achieved by percolation of the dispersed conducting polymer phase hosted in an insulating polymer matrix and by spin-coating or casting for film formation. However, only thin films of conducting polymers can be fabricated with these procedures, and the film morphologies are unstable when processed at temperatures above the glass transition temperature (T g ) of the matrix polymer. In addition, they have not been extensively used as organic electronic devices because their electrical conductivity and electronic mobilities are not quite sufficient. To overcome these drawbacks, we propose a new and different concept for producing doped p-conjugated polymer films that are stable at high temperatures, highly conductive, and highly transparent at the nanoscale by relying on a continuous process that does not use any matrix or binder polymers. By using this new procedure, we can also easily realize well-defined thin films that are crystalline with fine-pitched patterns.In this Communication, we report for the first time on the self-assembly of ultrathin conducting films of PEDOT having a polycrystalline structure prepared by using vapor-phase polymerization. The vapor-phase polymerization technique is a bottom-up processing method that utilizes the organic arrangement of macromolecules to easily produce ordered aggregates, including on the nanoscale, or prepare thin films of self-assembled molecules, micropatterns, or modified microstructures of pure conducting polymers, as shown in Scheme 1. The PEDOT-patterned films can be formed by microcontact printing [12,13] using the selective self-assembly of 3,4-ethylenedioxythiophene (EDOT) monomers. By using this method, several kinds of conductive PEDOT structures were assembled on a substrate film, and the thickness of the assembled PEDOT layer and the height of the grown pattern were easily controlled between 20 and 300 nm with a 3 lm pitch by varying deposition temperature and time in the vapor deposition chamber. (1) ...

Measurement Protocols for Reporting PEDOT Thin Film Conductivity and Optical Transmission: A Critical Survey

“…There is some evidence in literature to suggest that this may not have been dealt with appropriately. [32] Figure 1 shows the schematic for a four-point probe and polymer thin film. Strictly speaking, if the polymer being measured is less than an infinite plain, a correction needs to be applied.…”

Expeditious and eco-friendly hydrothermal polymerization of PEDOT nanoparticles for binder-free high performance supercapacitor electrodes

“…It can clearly be seen that the 2.5 MR FeCl 3 sample exhibits polymer growth as extended disordered dendritic growth in the ending face similar to the vapour phase polymerization method, which reveals the anisotropic crystal formation of the sample. 16 In the case of higher MR of FeCl 3 the dendritic type of polymer growth was restricted in the ending face, and resembles spherical growth. Thus the nanodendrite structures entwine with each other and construct plenty of diminutive pores in each cluster of dendrites, which effectively promote the possibility of large ion storage and ion transport.…”

“…16,17 Controllable nanostructures of PEDOT had been polymerized using high temperature vapour phase synthesis approaches such as physical vapour deposition or chemical vapour deposition and also solution-based chemical strategies including electrochemical synthesis and sol gel technique. 18,19 Moreover, highly conducting PEDOT surface layers have been achieved by oxidative chemical vapour phase polymerization, [20][21][22] evaporative vapour phase polymerization, 23 and ultrasonic spray polymerization methods.…”

Vapor Phase Polymerization Deposition Conducting Polymer Nanocomposites on Porous Dielectric Surface as High Performance Electrode Materials

“…VPP self-assembly deposition of PEDOT has been reported by some research teams, and theses VPP conducting polymer films show promising applications in solar cells and supercapacitors [19,20]. However, to our best knowledge, there is a lack of reported work to build PEDOT and PEDOT nanocomposites as SETC electrode films through VPP process.…”