51.4: High‐Efficiency White OLEDs with Built‐up Outcoupling Substrate

Abstract

A built-up outcoupling substrate with a micro-patterned high refractive index layer was developed in order to obtain both high efficiency and reliability for OLEDs. Light extraction efficiency of this substrate was about 47 %, and high efficacy of about 85 lm/W was achieved by the combination with an all phosphorescent white OLED.

Development of Extremely High Efficacy White OLED with over 100 lm/W

“…It is because of the high refractive indices of organic layers and ITO (n ~ 1.8) and glass substrate (n ~ 1.5), and most of generated light are confined within these high refractive-index layers as waveguide and substrate modes due to total internal reflection (TIR) at interfaces. We have already reported highly efficient light outcoupling technology achieved by an originally developed built-up light extraction substrate (BLES) which is composed of high refractive index materials [3][4][5]. Schematic of BLES is depicted in Figure 2.…”

High-efficiency Technology of White OLEDs

“…3. Two-unit all-phosphorescent white OLED Two-unit all phosphorescent white OLEDs with red, green and light blue phosphorescent emitting material were investigated [3,4]. Emissive layers of red, green and light blue were separated into two emissive units.…”

“…2. All-phosphorescent white OLED on the BLES has realized high efficacy of about 85 lm/W and quite long half-decay lifetime of over 100,000 h at 1,000 cd/m 2 [3,4]. In terms of efficiency, commercialized OLED has already exceeded that of incandescent bulb.…”

High Efficiency White OLEDs for Lighting

“…Figure 2 shows the newly developed schematic structure of the light outcoupling substrate. Some semi-spherical micro lens array (MLA) structures were fabricated with high refractive index resins on various transparent plastic films [10]. In order to reduce the light absorption in this structure, extremely transparent high refractive index plastic films and materials were selected.…”