基于吡咯并吡咯二酮和苯并噻二唑聚合物的合成及其近红外电致变色性能

给-受体型窄带隙聚合物是一类新型可见-近红外电致变色材料,虽然可调性强、颜色丰富,但是其电致变色性能如对比度、稳定性等需要进一步提高。 通过调节聚合物中构筑单元吡咯并吡咯二酮(DPP)、苯并噻二唑(BTZ)和噻吩(T)的比例(n(DPP):n(BTZ):n(T)分别为1:0:1、1.5:0.5:1、2:1:1和3:2:1),合成了4种新型窄带隙电致变色聚合物,研究聚合物结构和电致变色性能的关系。 研究发现,这类聚合物在近红外光谱区具有较高的对比度(ΔT:50%60%)和变色效率(CE:300600 cm²/C),尤其是在1550 nm处,聚合物P3的ΔT高达63%、P4的CE高达471 cm²/C。 相比之下,含有BTZ基团的聚合物的吸收更长、对比度更高且更稳定。 这为设计给-受体型高性能电致变色聚合物提供了新的思路。

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

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.