Abstract
A new building block, 1,4-di(3-alkoxy-2-thienyl)-2,5-difluorophenylene (DOTFP) with several desirable features such as high backbone planarity, suitably lying highest occupied molecular orbital (HOMO), and good solubility, was developed by inserting an electron-deficient difluorophenylene into the 3,3′-dialkoxy-2,2′-bithiophene (BTOR) unit. Three regioregular D-A1-D-A2 type polymers based on DOTFP and benzothiadiazole (BT) derivatives were synthesized and characterized by comparing with a D-A type BTOR-based polymer. The content of highly electron-rich alkoxythiophene is reduced by half in the DOTFP-based polymers versus that of the BTOR-based polymer analogue, which results in a deeper HOMO level and benefits high open-circuit voltage (Voc) in polymer solar cells (PSCs). Consequently, the DOTFP-ffBT-based solar cells exhibited a significantly improved power conversion efficiency (PCE) of 8.7% and an increased Voc of 0.84 V compared to the BTOR-ffBT-based solar cells with a PCE of 2.6% and a Voc of 0.49 V. Additionally, the DOTFP-based polymers showed improved charge transport properties and film morphology than the BTOR-based polymer BTOR-ffBT, resulting in simultaneous enhancement of the short-circuit current (Jsc) and fill factor (FF) in PSCs. These results demonstrate the great promise of the DOTFP building block for the construction of high-performance photovoltaic polymer semiconductors with increased Vocs.
Original language | English |
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Pages (from-to) | 5352-5363 |
Number of pages | 12 |
Journal | Macromolecules |
Volume | 51 |
Issue number | 14 |
DOIs | |
Publication status | Published - 2018 Jul 24 |
Bibliographical note
Funding Information:X.G. thanks National Science Foundation of China (NSFC, 21774055), Shenzhen Peacock Plan project (KQTD20140630110339343), Basic Research Fund of Shenzhen City (JCYJ20160530185244662), and the Guangdong Natural Science Foundation (2015A030313900). J.C. acknowledges Basic Research Fund of Shenzhen City (JCYJ20170817104319061) and the SUSTC Presidential Postdoctoral Fellowship. M.A.U. and H.Y.W. are grateful for the financial support from the NRF of Korea (2016M1A2A2940911 and 20100020209).
Publisher Copyright:
© 2018 American Chemical Society.
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry