Organic thin-film transistors with sub-10-micrometer channel length with printed polymer/carbon nanotube electrodes

An electrohydrodynamic (EHD) jet printing technique was used for direct printing of a conductive polymer combined with carbon nanotubes (CNT). The solutions mixture of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and carbon nanotubes (CNTs) wrapped with PSS served as a PEDOT:PSS/CNT composite ink for the EHD jet printing. The EHD jet-printed patterns of the PEDOT:PSS/CNT composite exhibited excellent dimensional stability and provided sub-10-micrometer channel lengths suitable for highly integrated organic thin-film transistors (OTFTs). The resulting pentacene OTFTs employing the channel length of 7 μm yielded the field-effect mobility of 0.03 ± 0.01 cm2/(V s). In addition, we investigated the electronic structure and the crystalline morphology at the interface between pentacene and the PEDOT:PSS/CNT composite electrode, as well as the contact resistance of the OTFTs by varying the channel length produced by the EHD jet printing process.