Tuning the rheology of polymer conducting inks for various deposition processes

Alizée Glasser (1, 2, 3) , Eric Cloutet (1, 2) , Georges Hadziioannou (1, 2) , Hamid Kellay (3)

1 LCPO - Laboratoire de Chimie des Polymères Organiques
2 Team 4 LCPO : Polymer Materials for Electronic, Energy, Information and Communication Technologies
3 LOMA - Laboratoire Ondes et Matière d'Aquitaine

Organic semi-conducting polymers are attractive for their competitive price and their low processability requirements. Aqueous solutions of these polymers can be deposited with a variety of processes to make thin, flexible and transparent films. Such films can be used as transparent electrodes in organic light emitting diodes or organic photovoltaic cells. Poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is the only PEDOT:polyanion commercially available. However, other counterions such as poly(4-styrene trifluo-romethyl(bissulfonylimide)) (PSTFSI) have been shown to stabilize PEDOT and give comparable conductive properties and transparency to the films. We show that the rheological properties of these two aqueous systems are especially different. For example PEDOT:PSTFSI inks can form a physical gel even at low concentrations, making it attractive for processing purposes while PEDOT:PSS shows only minor shear thinning behavior for concentrations as high as 1 %wt. This difference in behavior is due to structural differences between the polyanions: PSTFSI favors hydrogen bonding while PSS does not. Here, we present a systematic study of the rheological properties and the film properties of PEDOT:PSTFSI inks for different concentrations and using various deposition processes such as doctor blade, screen-printing, inkjet, and soft blade deposition. We show that such inks can be adapted to each of these processes by simply tuning the concentration, making their formulation simple while keeping comparable optoelectronic properties as commercial inks.

Mots clés: printed electronics; rheology; conducting polymer inks

Domaines: Polymères

Alizée Glasser, Eric Cloutet, Georges Hadziioannou, Hamid Kellay. Tuning the rheology of polymer conducting inks for various deposition processes. Chemistry of Materials, 2019, 31 (17), pp.6936-6944. ⟨10.1021/acs.chemmater.9b01387⟩. ⟨hal-02169663⟩