Synthesis and characterization of donor–acceptor type 4,4?bis(2,1,3-benzothiadiazole)-based copolymers

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• 作者：Piyush Anant^a ; Hannah Mangold^b ; Nigel T. Lucas^c ; Fré ; dé ; ric Laquai^b ; Josemon Jacob^a ;   ; ^{jacob@polymers.iitd.ac.in}
• 关键词：Donor&ndash ; acceptor type polymers ; 4 ; 4&prime ; -bis(2 ; 1 ; 3-benzothiadiazole) ; UV&ndash ; vis spectroscopy
• 刊名：Polymer
• 出版年：2011
• 出版时间：12 September 2011
• 年：2011
• 卷：52
• 期：20
• 页码：4442-4450
• 全文大小：1025 K
• ISSN：S0032386111006446

文摘

A series of novel donor–acceptor type polymers based on 4,4?bis(2,1,3-benzothiadiazole) were synthesized and characterized. Two soluble regioregular tail-to-tail and head-to-head coupled polymers, poly[7,7?bis(3-octyl-2-thienyl)-4,4?bis(2,1,3-benzothiadiazole)] poly[3TBB3T], and poly[7,7?bis(4-octyl-2-thienyl)-4,4?bis(2,1,3-benzothiadiazole)] poly[4TBB4T] were synthesized by FeCl₃-mediated oxidative polymerization. To further decrease the band gap of the polymers, vinylene spacers were incorporated into the polymer backbone by Stille coupling of the corresponding monomers and (E)-1,2-bis(tributylstannyl)ethene. A crystal structure of a monomer analog shows near planar arrangement of the aromatic units in the solid state. The optical properties of the monomers and polymers were investigated by steady-state absorption and photoluminescence spectroscopy. Cyclic voltammetry measurements indicate that the polymers could be employed as acceptor materials in polymer–polymer bulk heterojunction solar cells due to their low LUMO energy of about??.0?eV. A maximum photovoltaic power conversion efficiency of about 0.3% was observed for a 1:1 blend of regioregular poly(3-hexylthiophene) (rr-P3HT) and poly[4TBB4T] and the origin of the moderate efficiency is discussed by interpreting the device current–voltage characteristics, external quantum efficiency and incident light intensity dependence of the power conversion efficiency.