A red-to-gray poly(3-methylthiophene) electrochromic device using a zinc hexacyanoferrate/PEDOT:PSS composite counter electrode

作者：Hong Siang Fu; Chen Lin Chi^*

来源：Electrochimica Acta, 2010, 55(12): 3966-3973.

DOI：10.1016/j.electacta.2010.02.033

• Bistable display
• Electrochromic device (ECD)
• Poly(3-methylthiophene) (PMeT)
• PEDOT:PSS
• Zinc hexacyanoferrate (ZnHCF)

In this paper, we describe a novel red-to-gray poly(3-methylthiophene) (PMeT) electrochromic device (ECD) with the aid of a zinc hexacyanoferrate (ZnHCF)/PEDOT:PSS counter electrode. The application of ZnHCF to an ECD is first reported. ZnHCF has long suffered from poor deposition yield problem, but we demonstrate that a robust ZnHCF film can be prepared by spin coating of a liquid suspension composed of ZnHCF nanoparticles and PEDOT:PSS ink on ITO. It was found that the ZnHCF/PEDOT:PSS composite worked much better with PMeT than pure ZnHCF or pure PEDOT:PSS from both electrochemical and optical aspects. With a LiClO(4)/PC electrolyte, the PMeT ECD having ZnHCF/PEDOT:PSS as its counter electrode could be reversibly switched between its red state (>0.8 V) and its gray state (<0V). For a 2 cm x 2 cm prototype device, the response time for coloration was less than 1 s. The maximum transmittance modulation of the device could attain 45.3% at 750 nm, which resulted in a corresponding coloration efficiency of 336.8 cm(2)/C. The maximum contrast ratio was 5.45 at 720 nm. In addition, the charge capacity of the ECD could retain 95% of its original value after 10,000 cycles of cyclic voltammetry aging test, although an electrodeposited PMeT film alone could be cycled several hundred times only. To sum up, this work proposes a new, cost-effective transparent counter electrode and brings a stable, high visual-contrast PMeT ECD prototype for further development of a red-color bistable display.

• 出版日期2010-4-30