Highly Conductive Inkjet-Printed PEDOT:PSS Film under Cyclic Stretching

Inkjet-printed conductive polymer PEDOT:PSS films haveprovideda new developing direction for realizing the stretchable transparentelectrodes in optoelectronic devices. However, their conductivityand stretchability are limited as the presence of insulating PSS chains,rigid PEDOT conjugated backbone, and stronger inter-chain interactionsin the pristine polymer, respectively. Here, we report a PEDOT:PSSfilm with preferable electrical and mechanical performances by inkjet-printingthe formulated printable ink containing PEDOT:PSS, formamide (FA), d-sorbitol (SOR), sodium dodecyl benzene sulfonate (DBSS), andethylene glycol (EG). The inkjet-printed uniform PEDOT:PSS film exhibitsa high conductivity of 1050 S/cm and sheet resistance of less than145 omega/sq on both rigid and flexible substrates. Moreover, theresistance can remain stable after 200 cycles of stretching at 55%strain. The film also presents good stability during repetitive stretching-releasingcycles. The significantly enhanced conductivity of the film lies onthe conformational transition of the backbone by secondary dopingand post-treatment with FA as well as removing the excess PSS componentsafter phase separation between PEDOT and PSS. Meanwhile, SOR servesas a plasticizer to break the original hydrogen bonds between PSSHchains and provides larger free volume for polymer chain extension,which gives the PEDOT:PSS film the ability to tolerant cyclic tension.This is one of the optimal performances currently reported for inkjet-printedstretchable PEDOT:PSS films. The inkjet-printed PEDOT:PSS film withhigh conductivity, stretching properties, as well as good biocompatibilityexhibits promising prospects as anodes on optoelectronic devices.

Automated summary

Inkjet-printed conductive polymer PEDOT:PSS films have been developed as stretchable transparent electrodes in optoelectronic devices. By printing a formulated ink containing PEDOT:PSS, formamide, d-sorbitol, sodium dodecyl benzene sulfonate, and ethylene glycol, a uniform film with high conductivity and mechanical performance is achieved. The film shows a high conductivity of 1050 S/cm, sheet resistance of less than 145 omega/sq, and can maintain stability even after 200 cycles of stretching at 55% strain. The enhanced conductivity is due to the conformational transition of the backbone through secondary doping and post-treatment with formamide, as well as the removal of excess PSS components after phase separation.