Fluorinated Benzothiadiazole (BT) Groups as a Powerful Unit for High-Performance Electron-Transporting Polymers
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- Title
- Fluorinated Benzothiadiazole (BT) Groups as a Powerful Unit for High-Performance Electron-Transporting Polymers
- Authors
- Junghoon Lee; Moonjeong Jang; Sang Myeon Lee; Dohyuk Yoo; Tae Joo Shin; Oh, JH; Changduk Yang
- Date Issued
- 2014-11-26
- Publisher
- American Chemical Society
- Abstract
- Over the past few years, one of the most remarkable advances in the field of polymer solar cells (PSCs) has been the development of fluorinated 2,1,3-benzothiadiazole (BT)-based polymers that lack the solid working principles of previous designs, but boost the power conversion efficiency. To assess a rich data set for the influence of the fluorinated BT units on the charge-transport characteristics in organic field-effect transistors (OFETs), we synthesized two new polymers (PDPP-FBT and PDPP-2FBT) incorporating diketopyrrolopyrrole (DPP) and either single- or double-fluorinated BT and thoroughly investigated them via a range of techniques. Unlike the small differences in the absorption properties of PDPP-FBT and its nonfluorinated analogue (PDPP-BT), the introduction of doubly fluorinated BT into the polymer backbone induces a noticeable change in its optical profiles and energy levels, which results in a slightly wider bandgap and deeper HOMO for PDPP-2FBT, relative to the others. Grazing incidence X-ray diffraction (GIXD) analysis reveals that both fluorinated polymer films have long-range orders along the out-of-plane direction, and p-p stacking in the in-plane direction, implying semicrystalline lamellar structures with edge-on orientations in the solid state. Thanks to the strong intermolecular interactions and highly electron-deficient p-systems driven by the inclusion of F atoms, the polymers exhibit electron mobilities of up to 0.42 and 0.30 cm(2) V-1 s(-1) for PDPP-FBT and PDPP-2FBT, respectively, while maintaining hole mobilities higher than 0.1 cm(2) V-1 s(-1). Our results highlight that the use of fluorinated BT blocks in the polymers is a promising molecular design strategy for improving electron transporting performance without sacrificing their original hole mobility values.
- Keywords
- n-channel dominant FET; fluorinated benzothiadiazole; diketopyrrolopyrrole; fluorine; organic field-effect transistors (OFET); FIELD-EFFECT TRANSISTORS; THIN-FILM TRANSISTORS; LARGE-AREA ELECTRONICS; OPEN-CIRCUIT VOLTAGE; SOLAR-CELLS; CHARGE-TRANSPORT; SEMICONDUCTING POLYMERS; CONJUGATED POLYMERS; COUPLING REACTIONS; BUILDING-BLOCKS
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/13653
- DOI
- 10.1021/AM505925W
- ISSN
- 1944-8244
- Article Type
- Article
- Citation
- ACS APPLIED MATERIALS & INTERFACES, vol. 6, no. 22, page. 20390 - 20399, 2014-11-26
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