Printing organic-field effect transistors from semiconducting polymers and branched polyethylene

Organic electroactive materials, particularly semiconducting polymers, are at the forefront of emerging organic electronics. Among the plethora of unique features, the possibility to formulate inks out of these materials is particularly promising for the large-scale manufacturing of electronics at lower cost on a variety of soft substrates. While solution deposition of semiconducting materials is promising for developing printed electronics, the environmental footprint of the materials and related devices needs to be considered to achieve sustainable manufacturing. Towards the development of greener printed electronics, this work investigates the utilization of a non-toxic, environmentally-friendly solvent, namely branched polyethylene (BPE), to formulate semiconducting inks. Focusing on a diketopyrrolopyrrole-based (DPP) semiconducting polymer, shellac as dielectric, and BPE as the solvent, solutions were prepared in different concentrations and their rheological properties were characterized. Then, printing on polyethylene terephthalate (PET) substrates using two different techniques was performed to fabricate organic field-effect transistors (OFETs). Both printing techniques yielded OFETs with good performance and device characteristics, averaging approximately 10⁻² and 10⁻⁴ cm² V⁻¹ s⁻¹, respectively, for slot-die coating and direct-ink writing deposition. Notably, despite some difference in threshold voltages, OFETs produced via slot-die coating and direct-ink writing showed comparable charge mobilities to previously reported OFETs prepared from similar materials, particularly those prepared on silicon dioxide wafers. Overall, this work confirms the suitability of BPE to formulate semiconducting inks to develop printed electronics in a greener manner. The printing methodology developed in this work also open new avenues for the design of functional printed electronics and related technologies.