Achieving Low-Energy Driven Viologens-Based Electrochromic Devices Utilizing Polymeric Ionic Liquids

作者：Lu Hsin Che; Kao Sheng Yuan; Yu Hsin Fu; Chang Ting Hsiang; Kung Chung Wei; Ho Kuo Chuan^*

来源：ACS Applied Materials & Interfaces, 2016, 8(44): 30351-30361.

DOI：10.1021/acsami.6b10152

• electrochromic devices (ECDs)
• viologens
• UV-curing
• ionic liquids
• polymer electrolytes
• diffusion coefficient
• electrochemistry
• gel electrolytes

Herein, three kinds,of viologens-based electrochromic devices (ECDs) (heptyl viologen (HV(BF4)(2)), octyl viologen (OV(BF4)(2)), and nonyl viologen (NV(BF4)(2))) were fabricated utilizing ferrocene (Fc) as a redox mediator. Among them, the NV(BF4)(2)-based ECD exhibits the highest coloration efficiency (36.2 cm(2)/C) owing, to the lowest driving energy. Besides, switching between 0 and 1.2 V, the NV(BF4)(2)-based ECD shows a desirable initial transmittance change (Delta T = 56.7% at 605 nm), and long-term stability (Delta T = 45.4% after 4000 cycles). Furthermore, a UV-cured polymer electrolyte containing polymeric ionic liquid (PIL, 1-allyl-3-methylimidazolium bis(trffiuoromethylsulfonyl)imide) and ethoxylated trimethylolpropane triacrylate (ETPTA) was introduced to the NV(BF4)(2)-based ECD. By controlling the weight percentage of the PIL, different airing degrees of the polymer electrolytes were obtained and led to an improved stability of the NV(BF4)(2)-based ECD because, of the immobilization of NV(BF4)(2). This observation was explained by calculating the apparent diffusivity (D-app) of the redox species in the NV(BF4)(2)-based ECD under various curing degrees. In addition, increasing the amount of PIL leads to a lower driven energy needed for the NV(BF4)2-based ECD, following the same trend as the value of D-app. Among all NV(BF4)(2)-based ECDs, 20 wt % of PIL addition (20-PIL ECD) exhibits large transmittance change (Delta T = 55.2% at 605 nm), short switching times (2.13 s in coloring and 2.10 sin bleaching), high coloration efficiency (60.4 and 273.5 cm(2)/C at 605 nm, after excluding the current density at the steady state), and exceptional cycling stability (Delta T = 53.8% after moo cycles, or retained 97.5%' of its initial Delta T).

• 出版日期2016-11-9