White top-emitting organic light-emitting diodes employing a graded-index down-conversion layers

• Main Author: 鍾燁析
• Other Authors: Pei-Kuen Wei
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/07718130516535962393

碩士 === 國立臺灣海洋大學 === 光電科學研究所 === 101 === We demonstrated a highly efficient color conversion layers (CCLs) by using the polycarbonate (PC) films with double-sided tapered morphology for white organic light-emitting diodes. The tapered morphology is nanoimprinted by the AAO template with multistep anodization and etching process. After evaporating the phosphor (Alq3:DCJTB) on the one side of the patterned PC film, the proposed CCLs form a highly refractive index (RI) gradient nanostructures, which its index profile is gradually reduced from 1.8 (organic materials) to unity (air). The introduced RI gradient nanostructures can strongly extract the confined light in devices to achieve more efficient color conversion. By applying the patterned CCL on a top-emitting blue OLED as the capping layer, 178% color conversion ratio had been achieved, which was 3.77 times higher than flat CCL. The resulting luminous efficiency of white device with patterned CCL (4.9 cd/A, 1000 cd/m2) was twice higher than the efficiency of the flat device (2.1 cd/A, 1000 cd/m2).