PEDOTPSS sulfonic acid

PSS as a counterion for PEDOT is always used in excess, that is, as host polyelectrolyte (HPE). The molar ratio of thiophene groups to sulfonic acid groups in standard PEDOTPSS dispersions is in the range of 1 1.9 to 1 15.2, which corresponds to a weight ratio range of 1 2.5 up to 1 20. Since only one... 

Jonsson et al. used synchrotron radiation to study the kinetic energy of photoelectrons from the S(2p) core level in PEDOTPSS films in electron spectroscopy for chemical analysis (ESCA). Photoelectrons from the S(2p) core level can be used as a quantitative measure of sulfur atoms in the aromatic thiophene ring of PEDOT and sulfur atoms in the sulfonic acid unit of PSS in the top layer of the film. By variation of the energy of the photons, the escape depth of photoelectrons from the polymer film can be tuned and a depth profile of the film can be obtained. Using this technique the authors demonstrated that pristine PEDOTPSS films have a PSS rich surface. With a photon energy of 270 eV, 95% of the signal stems from the outmost 15 A and a clear dominance of PSS is observed (see Table 9.4). When NMP and sorbitol are used as additives and the film is dried at room temperature, no PSS rich... 

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