Cyclic voltammetry, conjugated polymers

Cyclic voltammetry revealed that the band gap was reduced effectively by attaching the conjugated thiophene side chains. Therefore, these polymers have been proposed for solar-cell applications [20]. 

A similar synthetic way to LBL electrodeposition of PT film has been designed by Advincula and coworkers [338]. They described electrodeposition of polysiloxane precursor polymer to form crosslinked conjugated PT ultrathin film. In this study, the precursor polymer contained a polysiloxane backbone with pendant electro active thiophene monomer, which was electropolymerized by cyclic voltammetry. The morphology of PT film was transformed from a relatively globular to membrane-like shape with increasing the number of cycles. 

The BODIPY moiety has been incorporated into conjugated polymer architectures both by electrochemical polymerization and Stille cross-coupling procedures. In the former case, the core was functionalized at the a-position with EDOT units and the final monomer was electropolymerized to provide the polymer P28. Cyclic voltammetry revealed remarkable reversibility of both n- and p-doping processes with a very narrow electrochemical bandgap (Eg = 0.8 eV) of the polymer that is highly attractive for application to organic photovoltaics (Chart 18.9). ... 

Electrochemical properties of three polymers were explored by cyclic voltammetry measurement (Fig. 4.lid). After introducing fluorine atoms, the reductive currents of both fluorinated polymers increase obviously and the reductive doping processes appear to be more reversible than those of BDPPV. Both HOMO and LUMO levels of FBDOPV-1 and FBDOPV-2 are lowered, but clearly the LUMO levels are more easily affected (Table 4.2). The LUMO levels of FBDOPV-1 and FBDOPV-2 reach -4.26 and -4.30, 0.16 and 0.20 eV lower than that of BDPPV. Computational results reveal that both fluorinated polymers exhibit almost planar conjugated backbones and their HOMOs and LUMOs are well delocalized along polymer backbones (Fig. 4.1 le). This contrasts with many donor-acceptor polymers, in which the LUMOs are mostly localized on the electron-deficient units of polymer backbones [27, 63]. 

The electrochemical properties of conjugated polymers can be characterized using cyclic voltammetry, the most convenient and reliable electrochemical technique. This method involves the measurement of current at the working electrode as a function of potential during the application of the triangular potential waveform. The current flow is a result of the oxidation/reduction processes and the concomitant ion flow that occurs in ICPs. Cyclic voltammetry provides a rapid determination of electrochemical transitions occurring, the potentials at which these occur, and the rate of these transitions. It is the most effective and versatile electrochemical technique available for the study of redox reactions. 

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