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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/24975

Title: Molecular weight tuning of low bandgap polymers by continuous flow chemistry: increasing the applicability of PffBT4T for organic photovoltaics
Authors: Pirotte, Geert
Agarkar, Shruti
Xu, Bing
Zhang, Junxiang
Lutsen, Laurence
Vanderzande, Dirk
Yan, He
Pollet, Pamela
Reynolds, John R.
Maes, Wouter
Marder, Seth R.
Issue Date: 2017
Citation: JOURNAL OF MATERIALS CHEMISTRY A, 5(34), p. 18166-18175
Abstract: Continuous flow chemistry has been shown to be a suitable method for the large-scale preparation of conjugated polymers with uniform structural and macromolecular characteristics, which is especially relevant when applying these materials in optoelectronic devices. The molecular weight and dispersity of conjugated polymers have a major effect on final device performance through a combination of processing and morphological considerations. In this work, the low bandgap polymer PffBT4T-2OD ('PCE-11'), which provides highly efficient bulk heterojunction solar cells, is synthesized by continuous flow chemistry using an easily mountable home-made apparatus. The influence of various reaction parameters on the material characteristics is investigated. Particular attention is devoted to tuning of the molecular weight, as this has a major impact on solubility and processability of the resultant polymer and, ultimately, solar cell performance. We find that temperature, monomer concentration, and injection volume of the polymerization mixture are significant parameters that can be used to optimize the control over molecular weight. The same protocol is then also applied to a structurally similar polymer with longer alkyl side chains, PffBT4T-2DT, affording important advantages in terms of processing due to its higher solubility. An average power conversion efficiency of 9.4% for bulk heterojunction solar cells using PC71BM as the acceptor phase is achieved based on this flow-synthesized polymer.
Notes: [Pirotte, Geert; Vanderzande, Dirk; Maes, Wouter] UHasselt Hasselt Univ, DSOS, Inst Mat Res, IMO IMOMEC, Agoralaan Bldg D, B-3590 Diepenbeek, Belgium. [Agarkar, Shruti; Xu, Bing; Zhang, Junxiang; Pollet, Pamela; Reynolds, John R.; Marder, Seth R.] Georgia Inst Technol, Sch Chem & Biochem, 901 Atlantic Dr, Atlanta, GA 30332 USA. [Agarkar, Shruti; Xu, Bing; Zhang, Junxiang; Pollet, Pamela; Reynolds, John R.; Marder, Seth R.] Georgia Inst Technol, Ctr Organ Photon & Elect, 901 Atlantic Dr, Atlanta, GA 30332 USA. [Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter] IMEC, IMOMEC, Univ Campus Wetenschapspk 1, B-3590 Diepenbeek, Belgium. [Yan, He] Hong Kong Univ Sci & Technol, Dept Chem, Kowloon, Hong Kong, Peoples R China. [Yan, He] HKUST Shenzhen Res Inst, 9 Yuexing 1st RD,Hitech Pk, Shenzhen 518057, Peoples R China.
URI: http://hdl.handle.net/1942/24975
DOI: 10.1039/c7ta05627c
ISI #: 000408592900049
ISSN: 2050-7488
Category: A1
Type: Journal Contribution
Appears in Collections: Research publications

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