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. Issue 72 (18th July 2016)

• Record Type: Journal Article
• Authors: Hsiow, Chuen-Yo; Lin, Yu-Hsiang; Raja, Rathinam; Rwei, Syang-Peng; Chiu, Wen-Yen; Dai, Chi-An; Wang, Leeyih
• Is Part Of: RSC advances. Volume 6:Issue 72(2016)
• Page Start: 67976
• Page End: 67985
• Publication Date: 2016-07-18
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra11738d
• Languages: English
• ISSNs: 2046-2069

Abstract

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. 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 . CopolymerP2 shows a down-shifted HOMO energy level, enhanced solubility, and red-shifted absorption, as compared withP1 ; 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 ofP1 can be recovered by simply inserting a few 2, 1, 3-benzothiadiazole units into the polythiophene main chain inP2 through a random copolymerization route to yield a terpolymer, P3, which possesses excellent crystallinity, thereby causing a three-fold increment in hole mobility. Furthermore, theP1 /PC61 BM, P2 /PC61 BM, andP3 /PC61 BM 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 .