Efficiency Improvement in a Powder-Based Flexible Electroluminescence Device using Ag Nanothin-Film-Coated Transparent Electrodes

Abstract

Powder-based electroluminescent (EL) devices have attracted attention as a technology for realizing flexible curved lighting or displays. However, low efficiency is a challenge to overcome practical applications. Herein, the characteristics of EL devices are analyzed according to the properties of an indium-tin-oxide (ITO) electrode, and EL devices containing a Ag nanothin-film for efficiency enhancement are reported. As the emission area of the as-prepared EL device decreases, the power loss per unit area increases, resulting in a low device efficiency. To decrease the power loss of the device, a several-nano meter-thick Ag thin film is formed over a polyethylene terephthalate film to obtain 88% transmittance and 10 omega sq(-1) sheet resistance. An EL paste is printed thereon, followed by upper electrode film stacking to fabricate an EL device with a sandwich structure. Compared to an ITO film-based device with 40 omega sq(-1) sheet resistance, the as-prepared EL film device consumes less power and exhibits approximate to 12% higher device efficiency. The possibility of powder-based EL film display by playing pattern images on 9 x 9 pixel arrays formed on Ag nanothin-film electrodes is confirmed. It is believed that the present results promote practical research on future devices, including stretchable and bendable EL displays.