Two-Dimensional Tetrathienonaphthalenes-Based Donor-Acceptor Copolymers: Synthesis, Isomeric Effect, and Organic Field-Effect Transistors
Journal
Macromolecules
Journal Volume
53
Journal Issue
18
Pages
7740-7748
Date Issued
2020
Author(s)
Liu, H.-H.
Chang, S.-L.
Huang, K.-H.
Cao, F.-Y.
Cheng, K.-Y.
Sun, H.-S.
Lai, Y.-Y.
Cheng, Y.-J.
Abstract
Two-dimensional alkylated αβ-TTN and βα-TTN were designed and synthesized. The cross-shaped αβ-TTN and βα-TTN moieties were polymerized to afford two isomeric polymers, Pαβ-TTNFBT40 and Pβα-TTNFBT40. Pαβ-TTNFBT40 using an α-aNDT unit in the main chain exhibited more red-shifted absorption and a smaller HOMO/LUMO band gap than Pβα-TTNFBT40 using β-aNDT in the main chain. Compared to Pβα-TTNFBT40 showing a curved backbone, density functional theory (DFT) calculations revealed that Pαβ-TTNFBT40 exhibited a quasi-linear polymeric backbone that induces stronger intermolecular interactions and higher molecular ordering in the solid state. Pαβ-TTNFBT40 exhibited an organic field-effect transistor (OFET) hole mobility of 1.12 × 10-2 cm2 V-1 s-1, which outperformed Pβα-TTNFBT40 by 1 order of magnitude (1.60 × 10-3 cm2 V-1 s-1). Through side-chain engineering and optimization, Pαβ-TTNFBT24 using a shorter 2-butyloctyl side chain further strengthened the intermolecular interactions. From grazing incidence wide-angle X-ray scattering (GIWAXS), Pαβ-TTNFBT24 adopted an edge-on π-πstacking orientation in a thin film, leading to an improved mobility of 1.75 × 10-1 cm2 V-1 s-1, which has exceeded the mobility of the one-dimensional α-aNDT-based PaNDTDTFBT (4.70 × 10-2 cm2 V-1 s-1). This research demonstrated that the two-dimensional structure is an effective strategy to achieve higher OFET mobility, and the geometry of the main chain played a more significant role than that of the side chain in determining the physical and packing properties of polymers.
SDGs
Type
journal article