Abstract
A series of polymer semiconductors incorporating 2,1,3-benzothiadiazole-5,6-dicarboxylicimide (BTZI) as strong electron-withdrawing unit and an alkoxy-functionalized head-to-head linkage containing bithiophene or bithiazole as highly electron-rich co-unit are designed and synthesized. Because of the strong intramolecular charge transfer characteristics, all three polymers BTZI-TRTOR (P1), BTZI-BTOR (P2), and BTZI-BTzOR (P3) exhibit narrow bandgaps of 1.13, 1.05, and 0.92 eV, respectively, resulting in a very broad absorption ranging from 350 to 1400 nm. The highly electron-deficient 2,1,3-benzothiadiazole-5,6-dicarboxylicimide and alkoxy-functionalized bithiophene (or thiazole) lead to polymers with low-lying lowest unoccupied molecular orbitals (-3.96 to -4.28 eV) and high-lying highest occupied molecular orbitals (-5.01 to -5.20 eV). Hence, P1 and P3 show substantial and balanced ambipolar transport with electron mobilities/hole mobilities of up to 0.86/0.51 and 0.95/0.50 cm2 V-1 s-1, respectively, and polymer P2 containing the strongest donor unit exhibited unipolar p-type performance with an average hole mobility of 0.40 cm2 V-1 s-1 in top-gate/bottom-contact thin-film transistors with gold as the source and drain electrodes. When incorporated into bulk heterojunction polymer solar cells, the narrow bandgap (1.13 eV) polymer P1 shows an encouraging power conversion efficiency of 4.15% with a relatively large open-circuit voltage of 0.69 V, which corresponds to a remarkably small energy loss of 0.44 eV. The power conversion efficiency of P1 is among the highest reported to date with such a small energy loss in polymer:fullerene solar cells.
Original language | English |
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Pages (from-to) | 42167-42178 |
Number of pages | 12 |
Journal | ACS Applied Materials and Interfaces |
Volume | 9 |
Issue number | 48 |
DOIs | |
Publication status | Published - 2017 Dec 6 |
Bibliographical note
Funding Information:S.Z. acknowledges financial support from the National Key R&D Program of Strategic Advanced Electronic Materials (No. 2016YFB0401100) and the National Natural Science Foundation of China (Grant No. 61574077). X.G. thanks Shenzhen Peacock Plan Project (KQTD20140630110339343) and Shenzhen Basic Research Fund (JCYJ20160530185244662). G.X. acknowledges the financial support from the Science and Technology Development Fund of Macau SAR (FDCT-116/2016/A3) and Start-up Research Grant (SRG2016-00087-FST) from Research & Development Office at University of Macau. M.A.U. and H.Y.W. are grateful to the financial support from the National Research Foundation (NRF) of Korea (2016M1A2A2940911, 20100020209).
Funding Information:
S.Z. acknowledges financial support from the National Key R&D Program of “Strategic Advanced Electronic Materials” (No. 2016YFB0401100) and the National Natural Science Foundation of China (Grant No. 61574077). X.G. thanks Shenzhen Peacock Plan Project (KQTD20140630110339343) and Shenzhen Basic Research Fund (JCYJ20160530185244662). G.X. acknowledges the financial support from the Science and Technology Development Fund of Macau SAR (FDCT-116/2016/A3) and Start-up Research Grant (SRG2016-00087-FST) from Research & Development Office at University of Macau. M.A.U. and H.Y.W. are grateful to the financial support from the National Research Foundation (NRF) of Korea (2016M1A2A2940911, 20100020209). We are grateful to Prof. Tae Joo Shin for the useful discussion and help with the 2D GIWAXS image processing. We thank Dr. Byeongdu Lee for the GISAXShop program (by) for data conversion at https://sites.google.com/site/byeongdu/ software.
Publisher Copyright:
© 2017 American Chemical Society.
Keywords
- ambipolar
- conjugated polymer
- energy loss
- organic solar cells
- organic thin-film transistors
ASJC Scopus subject areas
- General Materials Science