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

Hsiow, C.-Y.C.-Y.HsiowLin, Y.-H.Y.-H.LinRaja, R.R.RajaRwei, S.-P.S.-P.RweiChiu, W.-Y.W.-Y.ChiuCHI-AN DAILEE-YIH WANG2020-01-062020-01-062016https://scholars.lib.ntu.edu.tw/handle/123456789/444690Molecular 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/PC61BM, P2/PC61BM, 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. © The Royal Society of Chemistry 2016.[SDGs]SDG7Chains; Hole mobility; Photovoltaic effects; Self assembly; 2 ,1 ,3-Benzothiadiazole; Electron-deficient units; Molecular engineering; Photovoltaic applications; Polythiophene derivatives; Power conversion efficiencies; Random copolymerization; Two Dimensional (2 D); Conjugated polymersModified 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 applicationjournal article10.1039/c6ra11738d2-s2.0-84979517154https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979517154&doi=10.1039%2fc6ra11738d&partnerID=40&md5=f0814428390050199972d328480329ad