Chinese Journal of Applied Chemistry ›› 2018, Vol. 35 ›› Issue (2): 165-173.DOI: 10.11944/j.issn.1000-0518.2018.02.170045

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Synthesis and Properties of Near-Infrared Electrochromic Polymers Containing Diketopyrrolopyrrole,Benzothiadiazole and Thiophene

CHEN Xiuhongab,HU Liuyongab,QIAO Wenqianga*(),WANG Zhiyuana*()   

  1. aState Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022,China
    bUniversity of Chinese Academy of Sciences,Beijing 100049,China
  • Received:2017-02-27 Accepted:2017-05-09 Published:2018-02-01 Online:2018-01-29
  • Contact: QIAO Wenqiang,WANG Zhiyuan
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.21474102, No.21474105)

Abstract:

Donor-acceptor type polymers are new electrochromic materials which are tunable and colorfull. However, the electrochromic properties such as optical contrast and stability need to be further improved. Low band gap conjugated polymers containing diketopyrrolopyrrole(DPP), benzothiadiazole(BTZ) and thiophen (T) were synthesized and their electrochromic properties were studied. Four polymers P1~P4 were obtained by adjusting the molar ratio of the three monomers(n(DPP):n(BTZ):n(T)=1:0:1, 1.5:0.5:1, 2:1:1 and 3:2:1, respectively). The absorption and electrochromic properties of the polymers depend on the ratios of DPP, BTZ and T units in the polymers. It was found that these polymers have high optical contrast(ΔT:50%60%) and coloration efficiency(CE:300600 cm2/C) in the near-infrared region. In particular, ΔT of polymer P3 reached the high value of 63% and CE of polymer P4 was 471 cm2/C at 1550 nm. The polymers containing BTZ groups have higher optical contrast at both the near-infrared(NIR) region and the maximum absorption wavelength than that of polymer P1 in which the BTZ content is zero. Polymers containing BTZ unit shows better electrochromic stability, which is attributed to its higher oxidation potential and better electrochemical stability. It provides a new way to design high-performance electrochromic polymers.

Key words: electrochromism, donor-acceptor type polymers, spectroelectrochemistry, optical contrast, coloration efficiency, stability