A novel design of donor-acceptor polymer semiconductors for printed electronics: application to transistors and gas sensors

Jet printing of π-conjugated polymers synthesized through simple solution processes has been considered to be promising for the direct patterning of organic semiconductors on large-area substrates. However, it is still challenging to achieve direct patterns of high-performance polymer semiconductors through electrohydrodynamic jet printing because of the relatively low solubilities of donor-acceptor π-conjugated polymers which have high charge carrier mobilities and operation stabilities. A novel synthesis is proposed to obtain donor-acceptor π-conjugated polymer semiconductors suitable for printed electronics while exhibiting high performance of hole transport properties. The backbones and side chains of the donor-acceptor π-conjugated polymers are fully engineered to (1) achieve balanced jetting conditions and (2) provide time to induce the intermolecular self-assembly during the continuous printing. The printed polymers have similar morphologies and molecular orderings to those of spin-coated semiconductor films, which provide highly uniform electrical performances of organic field-effect transistors (OFETs) with a saturation mobility similar to those of the spin-coated films, up to 3.07 cm 2 V −1 s −1 . Furthermore, these high performances and operational stabilities suggest feasibility of the printed OFETs to be applied to ammonia gas sensors. Our study guides the design of π-conjugated polymers suitable for large-area printing processes to contribute to printed electronics. This work reports the molecular engineering of polymeric semiconductors to get highly soluble inks, which enables the uniform deposition of semiconductors and contributes to high-performance transistor and sensor devices.