Issue 4, 2017

Side-chain modulation of dithienofluorene-based copolymers to achieve high field-effect mobilities

Abstract

A ladder-type dithieno[3,2-b:6,7-b′]fluorene (DTF), where the central fluorene is fused with two outer thiophene rings at its 2,3- and 6,7-junctions, is developed. The pentacyclic DTF monomers were polymerized with dithienodiketopyrrolopyrrole (DPP) acceptors to afford three alternating donor–acceptor copolymers PDTFDPP16, PDTFDPP20, and PDTFDPP32 incorporating different aliphatic side chains (R1 group at DTF; R2 group at the DPP moieties). The side-chain variations in the polymers play a significant role in determining not only the intrinsic molecular properties but also the intermolecular packing. As evidenced by the 2-dimensional GIXS measurements, PDTFDPP16 with octyl (R1) and 2-ethylhexyl (R2) side chains tends to align in an edge-on π-stacking orientation, whereas PDTFDPP20 using 2-butyloctyl (R1) and 2-ethylhexyl (R2) adopts a predominately face-on orientation. PDTFDPP32 with the bulkiest 2-butyloctyl (R1) and 2-octyldodecyl (R2) side chains shows a less ordered amorphous character. The OFET device using PDTFDPP20 with a face-on orientation determined by GIXS measurements achieved a high hole-mobility of up to 5 cm2 V−1 s−1. The high rigidity and coplanarity of the DTF motifs play an important role in facilitating intramolecular 1-dimensional charge transport within the polymer backbones. The implementation of main-chain coplanarity and side-chain engineering strategies in this research provides in-depth insights into structure–property relationships for guiding development of high-mobility OFET polymers.

Graphical abstract: Side-chain modulation of dithienofluorene-based copolymers to achieve high field-effect mobilities

Supplementary files

Article information

Article type
Edge Article
Submitted
14 Sep 2016
Accepted
20 Jan 2017
First published
10 Feb 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2017,8, 2942-2951

Side-chain modulation of dithienofluorene-based copolymers to achieve high field-effect mobilities

C. Lee, Y. Lai, J. Hsu, P. Huang and Y. Cheng, Chem. Sci., 2017, 8, 2942 DOI: 10.1039/C6SC04129A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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