Toward Precision Control of Nanofiber Orientation in Conjugated Polymer Thin Films: Impact on Charge Transport

Abstract

The deposition of conjugated polymers is typically subject to chain-entanglement effects, which can severely hinder chain unfolding, alignment, and π−π stacking during rapid solution-coating processes. Here, long-range ordering and highly aligned poly(3-hexylthiophene) (P3HT) thin films were demonstrated by preprocessing the polymer solution with ultraviolet (UV) irradiation/solution aging and then depositing via the blade-coating method, which is compatible with roll-to-roll printing processes. The surface morphologies and optical anisotropy of deposited films revealed that the degree of chain alignment was greatly improved with increased levels of polymer assembly that can be precisely controlled by solution-aging time. The correlations between oriented nanofibrillar structures and their charge-transport anisotropy were further systematically investigated by blade coating pretreated solutions parallel and perpendicular to the direction of the source and drain electrodes. Interestingly, charge transport across the well-aligned P3HT nanofibers was more efficient than along the long-axis of nanofibrillar structures owing to enhanced intramolecular charge transport and tie-chains. The facile and scalable solution-coating method investigated here suggests an effective approach to induce anisotropic crystalline structures, which are readily obtained by directly controlling their intrinsic solution properties without the need for extrinsic techniques such as surface templating or shearing blade patterning.

Diketopyrrolopyrrole‐based polymer fibrils formation by changing molecular conformation during film formation

“…The relative intensity of 0‐0/0–1 was increased from 0.98 to 1.78 by adding DIO. The higher intensity of 0‐0/0–1 by adding DIO indicated the longer effective conjugation length . To investigate the origin of improving conjugation length by adding DIO, we prepared the samples with CN.…”

Conjugated polymer single crystals and nanowires

“…Thus, the mobility of nanowire film TEF is much lower than that of single crystal or nanowire FET. Egap et al and Reichmanis et al prepared ordered P3HT nanowires almost simultaneously by offering a shear force during the film forming process . Figure A shows the schematic diagram of nanowire films deposited on an FET device substrate with a shear force .…”

Liquid Crystal Ordering on Conjugated Polymers Film Morphology for High Performance

“…(i) Long‐range orientation benefitting the charge transport . (j) The formation of preaggregates in solution before blade coating results in a higher anisotropy in oriented films Reprinted (adapted) with permission from ref. .…”