Double-shot inkjet printing of donor–acceptor-type organic charge-transfer complexes: Wet/nonwet definition and its use for contact engineering

We developed the double-shot inkjet printing technique for manufacturing the uniform polycrystalline thin films of organic charge-transfer complexes with a well-defined patterning on the substrate surfaces. The technique utilizes the wet/nonwet surface modification to confine the intermixed droplets of individually-printed donor and acceptor inks in a predefined area, which results in the picoliter-scale instantaneous complex formation. By the method, we obtained synthetic-metal patterned deposits of tetrathiafulvalene–tetracyanoquinodimethane with smooth thickness distribution and highly c-axis orientation, where the preference for the 1:1 complex formation is clearly demonstrated. We also discuss the use of the patterned deposits for the contact engineering of organic thin-film transistors.