Color e-Paper Technology with Electrochemistry

The demand for global environmental conservation and decrease of CO₂ evolution require the development of “new imaging media”, instead of paper.  This is called “electronic paper (e-Paper)”.  Electrochromism (EC) is defined as a reversible color change by electrochemical reaction and has several features such as color variation, memory property and so on.  Electrochromic display (ECD) is therefore a potential candidate to realize full color e-Paper.  EC materials showing color changes from clear to the three primary colors such as RGB or CMY should be required to realize full color e-Paper.

    This paper focuses on novel e-paper technology with electrochemical reaction.  First, we will show our recent results on EC materials and devices which show three primary colors (CMY) in subtractive color mixture system^{1, 2}.   Electrodeposition is also attractive method to create colors^3-5.  We will discuss the mechanism of electro-deposition and a wide range of its applications. 

We also demonstrated novel display device with dual reflective and emissive modes.  This is called dual mode display (DMD).  DMD enables both reflective and emissive mode of representation which can be chosen as a situation demand.  We fabricated DMD by combining both electrochromic (EC) and electrochemiluminescence (ECL) materials in a single cell^{6, 7}.  The device functions as an EC cell in the reflective mode, and as an ECL cell in the emissive mode.

References;   1) Solar Energy Materials and Solar Cells, 92 136 (2008), 2) Solar Energy Materials and Solar Cells, 104, 140 (2012), 3) Adv. Mater., 24, OP122 (2012), 4) Adv. Mater., 25, 3197 (2013), 5) Chem. Mater, 26, in press (2014). 6) Chem. Lett., 39, 1309 (2010), 7) Phys. Chem. Chem. Phys., 13, 19420 (2011).