Thiophene-Fused Benzothiadiazole: A Strong Electron-Acceptor Unit to Build D–A Copolymer for Highly Efficient Polymer Solar Cells
作者:Pengcheng Zhou、Zhi-Guo Zhang、Yongfang Li、Xingguo Chen、Jingui Qin
DOI:10.1021/cm501052a
日期:2014.6.10
A novel strong electron-acceptor, thieno[2,3-f-]-2,1,3-benzothiadiazole-6-carboxylate (BTT), was first designed and synthesized. By introducing two thienyl groups into BTT and then copolymerizing with thienyl group substituted benzo[1,2-b:4,5-b']dithiophene (BDTT) unit, a low band gap D A copolymer (PBTT-TBDTT) was obtained. Compared with its polymer analogue (PBT-TBDTT) with benzothiadiazole (BT) as an acceptor, PBTT-TBDTT exhibits stronger intramolecular charge transfer. Thus, it shows much broader absorption covering almost the whole visible light region (in the range of 300-850 nm) and narrower optical band gap around 1.45 eV with a large IP (ionization potential) at 5.35 eV. The maximum efficiency of PBTT-TBDTT based device reaches 6.07% which is much higher than that of PBT-TBDTT (3.24%), indicating that BTT unit is a promising electron-acceptor moiety to construct low band gap D A copolymers for PSCs with high photovoltaic performances.