Modified structure of two-dimensional polythiophene derivatives by incorporating electron-deficient units into terthiophene-vinylene conjugated side chains and the polymer backbone: synthesis, optoelectronic and self-assembly properties, and photovoltaic application
Abstract
Molecular engineering on the conjugated side chains of two-dimensional (2D) conjugated polymers was conducted and its effect on the optical, electronic, self-assembly and photovoltaic properties was investigated. A new monomer, M2, was prepared by capping (E)-3′-(2-(2,5-dibromothiophen-3-yl)vinyl)-4,4′′-bis(2-ethylhexyl)-2,2′:5′,2′′-terthiophene, M1, with two heptanoyl groups, and then coupled with 5,5′-bis(trimethylstannyl)-2,2′-bithiophene via microwave-assisted Stille polymerization to produce a series of polythiophene derivatives with terthiophene-vinylene conjugated side chains, TTV–PTs. Copolymer P2 shows a down-shifted HOMO energy level, enhanced solubility, and red-shifted absorption, as compared with P1; however, the bulky side chains significantly disrupt the coplanarity of thiophene rings in the polymer backbone and the ability to self-assemble into an ordered structure. The GIXRD measurements reveal that the original crystallinity of P1 can be recovered by simply inserting a few 2,1,3-benzothiadiazole units into the polythiophene main chain in P2 through a random copolymerization route to yield a terpolymer, P3, which possesses excellent crystallinity, thereby causing a three-fold increment in hole mobility. Furthermore, the P1/PC_(61)BM, P2/PC_(61)BM, and P3/PC61BM solar devices exhibit power conversion efficiencies of 3.89%, 1.52%, and 4.17%, respectively, under AM1.5G illumination with an intensity of 100 mW cm^(−2).
Additional Information
© 2016 The Royal Society of Chemistry. Received 05 May 2016, Accepted 08 Jul 2016; First published online 08 Jul 2016. This research was financially supported by National Taiwan University, Academia Sinica (AS-103-SS-A02), and the Ministry of Science and Technology of the Republic of China (MOST 102-2113-M-002-003-MY3; MOST 105-3113-E-102-010). The authors thank the instrumentation center sponsored by Ministry of Science and Technology and National Taiwan University for NMR, elemental analysis and TEM experiments.Attached Files
Published - c6ra11738d.pdf
Supplemental Material - c6ra11738d1_si.pdf
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Additional details
- Eprint ID
- 69308
- Resolver ID
- CaltechAUTHORS:20160729-112444002
- National Taiwan University
- AS-103-SS-A02
- Academia Sinica
- 102-2113-M-002-003-MY3
- Ministry of Science and Technology (Taipei)
- 105-3113-E-102-010
- Ministry of Science and Technology (Taipei)
- Created
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2016-07-29Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field