Tech

Reaction Mechanism of the Electrochemically Driven Reflective-Emissive Dual-mode Display Cell

Yuichi Watanabea,b, Yukie Ibataa, Kazuki Nakamuraa, Norihisa Kobayashia a Graduate School of Advanced Integration Science, Chiba University b Research Fellow of the Japan Society for the Promotion of Science 1-33 Yayoi-chou, Inage-ku ,Chiba-Shi, Chiba, 263-8522, Japan watanabe_yuichi@graduate.chiba-u.jp Display devices are classified into two groups such as the reflective mode and the emissive mode. The reflective mode displays such as printed material and electronic papers have a high visibility under daylight condition, but are useless in dark place. Although the other emissive mode displays such as plasma display panel and organic light-emitting diodes can be seen clearly in a dark room, these have difficulty in seeing under direct sunlight. In addition, the reflective displays are driven by lower energy consumption than the emissive displays. Dual-mode display (DMD) is designed to exploit both advantages of the reflective display and the emissive display. The DMD has both the reflective and the emissive display mechanism, and we can choose either as the situation demands. We invented novel reflective-emissive DMD cell (Fig.1) using electrochemical reaction [1]. We employ electrochromism (EC) and electrochemiluminescent (ECL) as the reflective and the emissive mode in the DMD cell, respectively. EC material is fixed on one electrode as the reflective layer, and ECL material is fixed on the other electrode as the emissive layer. Our DMD cell shows the reflective mode under DC bias application and the emissive mode under AC bias application. In the reflective mode (Fig.1a), the color change of EC material occurs by oxidative or reductive in the reflective layer. In contrast, emission of ECL material does not occur because only one cation radical or anion radical is generated in emissive layer. In the emissive mode (Fig.1b), the emission of ECL material occurs by...