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Conductivity enhancement and improved water resistance of PEDOT:PSS films via cross-linking with oxetanes

Silva, S. ; Santos, L. ; Galvão, A. ; Morgado, J. ; Charas, A.

Conductivity enhancement and improved water resistance of PEDOT:PSS films via cross-linking with oxetanes, Proc GLOBAL CONFERENCE ON POLYMERS, PLASTICS AND COMPOSITES PPC-2022, Budapest, Hungary, Vol. , pp. - , March, 2022.

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Abstract
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most interesting organic conducting materials, due to its high conductivity, tunable work function, electrochemical activity, high transparency in the visible spectral range, excellent thermal stability, and easy processing from aqueous dispersions. It has shown important applications in organic electronics and bioelectronics, as hole-transport layer, ink-jet printed electrodes, electro-active element in organic implantable devices, among many more. However, PEDOT:PSS films often suffer from cracking, delamination or re-dispersion when interfacing aqueous solutions and, on the other hand, their conductivity is insufficient for some applications. We have developed a new method that renders PEDOT:PSS films insoluble in aqueous media through the covalent cross-linking of PSS chains with a polyether formed in situ from the polymerization of oxetane reagents, added to the PEDOT:PSS aqueous dispersions. In addition, the electrical conductivity of the films is simultaneously increased in more than 3 orders of magnitude, without the need of adding any doping agents or thermally annealing the films above regular drying conditions, while high transmittance in the visible is maintained. Thus, the new method presents advantages in comparison with the reported approaches. We will present a systematic study of the films´ characteristics and explore their applications in optoelectronic devices