Floating-non-solvent method for inducing the formation of highly crystalline conjugated polymer nanofibrils in the solution state for high-performance organic transistors

We developed a facile dip-coating printing method using a floating non-solvent (FNS) that produced highly crystalline polymer semiconductor nanofibrils. This FNS dip-coating method used a bi-phasic solution comprising a polymer semiconductor main solution, on top of which was floated a non-solvent phase. We demonstrated that the non-solvent diffused into the underlying polymer-containing main solution and induced the formation of highly crystalline polymer nanofibrils over time. We tested four different floated non-solvent phases and systematically compared the miscibility of the floated phases and the underlying polymer solution as a function of their Hansen solubility parameters (HSPs). We demonstrated that the HSP difference was correlated with the degree to which the floated non-solvent and the main solution intermixed, which affected polymer crystallization, the solution state stability, and the thickness of the resulting dip-coated P3HT thin film over time. The FNS-processed dip-coated thin films were used to fabricate P3HT transistors, and the field-effect charge carrier mobilities of the devices were measured.