Date

Place

Room B (Room 324)
49. OLED Optics
August 21, 2015 (Friday)
11:00 ~ 12:35

[49-2]
11:25 ~ 11:40
Title:An Embossing Structure Improving Viewing Angle and Device Efficiency Characteristics of Organic Light Emitting Diode
Keunsoo Lee, Jonghee Lee, Jeong-Ik Lee, Doo-Hee Cho, Jong Tae Lim, Chul Woong Joo, Joo Yeon Kim (ETRI, Korea), Byeong-Kwon Ju (Korea Univ., Korea), and Jaehyun Moon (ETRI, Korea)
Abstract: Conventional organic light emitting diode (OLED) has an intrinsic limitation that only ~20% of light can be escaped to air due to various light confinement mechanisms. The limitation induces energy loss and device lifetime problem. Besides, viewing angle distortion problem results from microcavity effect has to be overcome. We have fabricated an embossing structure which can resolve the viewing angle distortion and light confinement problems. The embossing structure was attached on the glass substrate of a green phosphorescence OLED. In order to investigate the influence of microcavity, the thickness of electron transport layer (ETL) was varied 30nm and 60nm. The enhancement of OLED with the embossing structure was 40.7% for 60nm ETL and 30.1% for 30nm ETL. Difference of EQE by ETL thickness is due to microcavity effect. For 30nm of ETL, optical length of devices was optimized to obtain high EQE. For 30nm thickness, more enhancement of EQE has been obtained instead viewing angle distortion appeared. By applying the embossing structure, we obtained the stabilized viewing angle characteristic as well as the enhanced EQE. The simple embossing structure can be applied portably to various optical applications in the aspect of enhancing efficiency and spectrum stabilization.? ????????????
PDF Download

Type