Metal–Ligand Based Mechanophores Enhance Both Mechanical Robustness and Electronic Performance of Polymer Semiconductors
Journal
Advanced Functional Materials
Journal Volume
31
Journal Issue
11
Date Issued
2021
Author(s)
Wu, Hung-Chin
Lissel, Franziska
Wang, Ging-Ji Nathan
Koshy, David M.
Nikzad, Shayla
Yan, Hongping
Xu, Jie
Luo, Shaochuan
Matsuhisa, Naoji
Cheng, Yuan
Wang, Fan
Ji, Baohua
Li, Dechang
Xue, Gi
Bao, Zhenan
Abstract
The backbone of diketopyrrolopyrrole-thiophene-vinylene-thiophene-based polymer semiconductors (PSCs) is modified with pyridine (Py) or bipyridine ligands to complex Fe(II) metal centers, allowing the metal–ligand complexes to act as mechanophores and dynamically crosslink the polymer chains. Mono- and bi-dentate ligands are observed to exhibit different degrees of bond strengths, which subsequently affect the mechanical properties of these Wolf-type-II metallopolymers. The counter ion also plays a crucial role, as it is observed that Py-Fe mechanophores with non-coordinating BPh4– counter ions (Py-FeB) exhibit better thin film ductility with lower elastic modulus, as compared to the coordinating chloro ligands (Py-FeC). Interestingly, besides mechanical robustness, the electrical charge carrier mobility can also be enhanced concurrently when incorporating Py-FeB mechanophores in PSCs. This is a unique observation among stretchable PSCs, especially that most reports to date describe a decreased mobility when the stretchability is improved. Next, it is determined that improvements to both mobility and stretchability are correlated to the solid-state molecular ordering and dynamics of coordination bonds under strain, as elucidated via techniques of grazing-incidence X-ray diffraction and X-ray absorption spectroscopy techniques, respectively. This study provides a viable approach to enhance both the mechanical and the electronic performance of polymer-based soft devices. ? 2021 Wiley-VCH GmbH
Subjects
Complexation; Hall mobility; Hole mobility; Ligands; Metals; Polymers; Thiophene; X ray absorption spectroscopy; Bipyridine ligands; Diketopyrrolopyrroles; Electrical charges; Electronic performance; Grazing incidence X-ray diffraction; Mechanical robustness; Molecular ordering; Polymer semiconductors; Iron compounds
SDGs
Type
journal article