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Direction‐Selectable Ultra‐Highly Oriented State of Donor–Acceptor Conjugated Polymer Induced by Slow Bar Coating Process
Author(s) -
Yabuuchi Yuta,
Minowa Yu,
Kajii Hirotake,
Nagano Shusaku,
Fujii Akihiko,
Ozaki Masanori
Publication year - 2021
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.202100313
Subject(s) - materials science , conjugated system , coating , polymer , acceptor , crystallinity , chemical engineering , perpendicular , fabrication , thiophene , nanotechnology , composite material , organic chemistry , chemistry , mathematics , medicine , physics , geometry , alternative medicine , condensed matter physics , pathology , engineering
The molecular orientation of π‐conjugated polymers is a significant factor for the electrical properties of polymer‐based printable devices, because π‐conjugated polymers exhibit a notable fast carrier transport property along their main chain. Although various coating processes are suggested, the challenge to realize high‐degree alignment by one‐step coating without pre‐ or post‐treatments still remains. In this paper, it is reported on the fabrication of an extremely highly aligned thin film by a slow bar coating process using a donor–acceptor π‐conjugated polymer with great aggregability. The 2D order parameter achieved is 0.9, which is the highest obtained among the alignment methods with a one‐step coating process. Furthermore, the direction of the main chain is selectively oriented parallel or perpendicular to the coating direction depending on the solution concentration with high orientation degree. This unique orientation phenomenon seems to be related to the nematic liquid crystallinity of poly[2,5‐(2‐octyldodecyl)‐3,6‐diketopyrrolopyrrole‐alt‐5,5‐(2,5‐di(thien‐2‐yl)thieno [3,2‐b]thiophene)] aggregates formed by the slow coating process. The orientation dynamics is discussed by taking the structure and behavior of the aggregates in the solution into account.