From Chlorinated Solvents to Branched Polyethylene: Solvent-Induced Phase Separation for the Greener Processing of Semiconducting Polymers

Despite having favorable optoelectronic and thermomechanical properties, the wide application of semiconducting polymers still suffers from limitations, particularly with regards to their processing in solution which necessitates toxic chlorinated solvents due to their intrinsic low solubility in common organic solvents. This work presents a novel greener approach to the fabrication of organic electronics without the use of toxic chlorinated solvents. Low-molecular-weight non-toxic branched polyethylene (BPE) is used as a solvent to process diketopyrrolopyrrole-based semiconducting polymers, then the solvent-induced phase separation (SIPS) technique is adopted to produce films of semiconducting polymers from solution for the fabrication of organic field-effect transistors (OFETs). The films of semiconducting polymers prepared from BPE using SIPS show a more porous granular morphology with preferential edge-on crystalline orientation compared to the semiconducting polymer film processed from chloroform. OFETs based on the semiconducting films processed from BPE show similar device characteristics to those prepared from chloroform without thermal annealing, confirming the efficiency and suitability of BPE to replace traditional chlorinated solvents for green organic electronics. This new greener processing approach for semiconducting polymers is potentially compatible with different printing techniques and is particularly promising for the preparation of porous semiconducting layers and the fabrication of OFET-based electronics