Secondary doping in poly(3,4‐ethylenedioxythiophene):Poly(4‐styrenesulfonate) thin films

Abstract

The electrical and structural properties of poly (3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin films deposited from aqueous dispersion using different concentrations of selected secondary dopants are studied in detail. An improvement of the electrical conductivity by three orders of magnitude is achieved for dimethyl sulfoxide, sorbitol, ethylene glycol, and N,N-dimethylformamide, and the secondary dopant concentration dependence of the conductivity exhibits almost identical behavior for all investigated secondary dopants. Detailed analysis of the surface morphology and Raman spectra reveals no presence of the secondary dopant in fabricated films, and thus the dopants are truly causing the secondary doping effect. Although the ratio of benzenoid and quinoid vibrations in Raman spectra is unaffected by doping, the phase transition in PEDOT:PSS films owing to doping is confirmed. Further analysis of temperature-dependent conductivity reveals 1D variable range hopping (VRH) charge transport for undoped PEDOT:PSS, whereas highly conductive doped PEDOT:PSS films exhibit 3D VRH charge transport. We demonstrate that the charge-hopping dimensionality change should be a fundamental reason for the conductivity enhancement.

Layered composites of PEDOT/PSS/nanoparticles and PEDOT/PSS/phthalocyanines as electron mediators for sensors and biosensors

“…It has been reported that the addition of different dopants to an aqueous solution of PEDOT/PSS produces an enhancement in the conductivity of PEDOT/PSS films obtained from the solution [29–30]. In our case, the additives were deposited as a thin film on the top of the PEDOT/PSS layer and the same effect was observed.…”

A PSS‐Free PEDOT Conductive Film Supported by a Hierarchical Nanoporous Layer Glass

“…However, this conductivity is less than recently reported highly conductive PEDOT‐based films: crystalline PEDOT films (5000 S cm −1 ) and structurally optimized “metallic” PEDOT/PSS thick films (700 S cm −1 ), for example. Though the PEDOT was assumed to occupy the whole area of HNL in the above estimation, the PEDOT volume should be much less than the assumption due to following two reasons.…”

“…Furthermore, the microscopic optimizations adopted in the studies mentioned above have not been carried out in this study. Hence, we think that the PSS‐free PEDOT developed in this work is still open to conductivity improvement.…”

Flexible and Cellulose-based Organic Electronics

“…[11] The process often involves adding a high boiling point organic solvent, such as sorbitol or dimethyl sulfoxide, to the PEDOT:PSS emulsion before processing thin films followed by thermal annealing. [12] Alternatively, the polymer film can be immersed in the high boiling point solvent. Although the mechanism of the increase in conductivity is not fully understood, most evidence points to a morphological change.…”