The influence of carbon nanotubes in inkjet printing of conductive polymer suspensions

In this study, inkjet printing inks were formulated by combining the processability of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) to the high conductivity of carbon nanotubes (CNTs). Conductive patterns were deposited on polymer films by piezoelectric inkjet printing. Several settings of printing were explored and analyzed by morphological observations and sheet resistance measurements. Performances of several CNTs were evaluated (single-walled, multi-walled and functionalized CNTs). Patterns can have sheet resistances from 10 537 to 225 Omega/sq between two families of CNTs. Functionalized CNTs with polyethylene glycol functions appeared to be the best candidates for printed electronics. This best combination allows us to obtain sheet resistances as low as 225 Omega/sq which is up to now one of the lowest resistances obtained by inkjet printing. This work also discusses the CNT network performances and emphasizes the degradation of electrical properties linked to the use of surfactants. This study represents an important step for the integration of CNTs in printed electronics applications and offers new opportunities to produce cost-effective electronics.