Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (9): 945-953.DOI: 10.6023/A20050170 Previous Articles     Next Articles



刘情情a,b, 张逸寒a,b, 高灿a, 王天禹a, 胡文平a,c, 董焕丽a,b   

  1. a 中国科学院化学研究所 北京分子科学国家重点实验室 有机固体重点实验室 北京 100190;
    b 中国科学院大学 北京 100049;
    c 天津大学理学院 天津市分子光电科学重点实验室 天津 300072
  • 投稿日期:2020-05-16 发布日期:2020-06-24
  • 通讯作者: 董焕丽
  • 基金资助:

Synthesis and Property Study of Field-effect Emissive Conjugated Polymers Based on Styrene and Benzothiadiazole

Liu Qingqinga,b, Zhang Yihana,b, Gao Cana, Wang Tianyua, Hu Wenpinga,c, Dong Huanlia,b   

  1. a Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China;
    c Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300072, China
  • Received:2020-05-16 Published:2020-06-24
  • Supported by:
    Project supported by the National Key Research and Development Project (Nos. 2017YFA0204503, 2018YFA0703200), the National Natural Science Foundation of China (Nos. 61890943, 51725304) and Beijing National Laboratory for Molecular Sciences (BNLMS-CXXM-202012).

Conjugated polymer materials with good photoelectric performance, solution processing ability and flexibility are widely used as active layers in optoelectronic devices. Here, using Stille and Suzuki coupling reactions, we designed and synthesized two new conjugated polymers, poly(1,2-bis(2,5-bis(iso-octyloxy)phenylenevinylene-2,1,3-benzothiadiazole)) (PVBT) and poly(1,2-bis(2,5-bis(n-octyloxy)phenylenevinylene-2,1,3-benzothiadiazole)) (nPVBT), which contain structural element styrene fragments and an conjugated unit benzothiadiazole. Styrene fragments are conducive to luminescent properties of materials, such as phenylenevinylene (PPV) derivatives, while benzothiadiazole unit is electron withdrawing, and matches with many structural units of a donor. The conjugated polymers were characterized by gel permeation chromatography (GPC), elemental analysis and differential scanning calorimetry (DSC). The results indicate that each of these two polymers has good thermal stability. Their melting points were around 240~250℃ and decomposition temperatures around 380℃. Due to the presence of the structural alkoxy chains, these two polymers exhibit good solubility, which is conducive to solution-processed film formation. PVBT and nPVBT have strong fluorescence characters with maximum emission in the range of 590~605 nm. The photoluminescence quantum yield of these two polymers in dichloromethane solution (1×10-5 mol·L-1) is 23%~35%, and 12%~20% in solid films, which are annealed at 180℃ for 10 min. Due to benzothiadiazole's regulation of molecular energy levels, the highest occupied molecular orbital (HOMO) energy level of PVBT and nPVBT were modulated to be -5.73 and -5.61 eV, and the lowest unoccupied molecular orbital (LUMO) energy level were -3.37 and -3.32 eV, respectively. Typical p-type transporting property was determined by using PVBT and nPVBT films as active layers in organic field effect transistors. Because of the improved conjugation of the skeleton structures and the close packing between benzothiadiazole of main chains, these two conjugated polymers both exhibit efficient charge transport characteristics with saturation hole carrier mobility is up to 1.1×10-4 cm2·V-1·s-1 and high switching on/off ratio of 103~104. This work provides new insight into the development of high-performance optoelectronic conjugated polymer materials and sheds light on the research of organic optoelectronic integrated devices.

Key words: styrene, benzothiadiazole, strong emission, field-effect transporting property