Effects of Nano Carrier-Regulating Layer on Organic Light-Emitting Diode Devices

• Main Author: 曾俊儒
• Other Authors: 周卓煇
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/00352646958359718941

博士 === 國立清華大學 === 材料科學工程學系 === 101 === In this study, we develope deep-blue and pseudo-natural light organic light-emitting diodes (OLEDs) with nano carrier-regulating layers, and investigate the effects of carrier-regulating layer on organic light-emitting diode devices. For high efficiency deep-blue OLED, the device was prepared by incorporating a florescent blue material 2,7-bis-{2[phenyl(m-tolyl)amino]-9,9- dimethyl-fluorene-7-yl}-9,9-dimethylfluorene with the variation of the number, thickness , and position of the carrier regulating layers employed to improve the device efficiency. Without the aid of any carrier modulation layer, the deep-blue OLED shows a power efficiency of 1.7 lm W-1 with CIE coordinates of (0.143, 0.098) at 1,000 cd m-2. The respective power efficiency is increased from 1.7 to 2.1 and 2.2 lm W-1 as a single- and double-carrier modulation layers were incorporated. The respective peak luminance also increases from 5,250 to 7,620 and 9,130 cd m-2, an increment of 45% and 74%. The marked brightness improvement may be attributed to the incorporated carrier regulating layers that effectively lead carriers to recombine in a wider zone. Moreover, the blue emission can be tuned deeper by varying the incorporation position of the carrier modulation layer and the emissive layer thickness. For pseudo-natural light OLED, the multiple-band pseudo-natural light OLED device was prepared by the spectral simulation and device structure designed with double carrier regulating layers and multiple emissive layers with six blackbody-radiation complementary emitters that form a color gamut to cover the blackbody-radiation locus. Natural light emits like the blackbody-radiation, which exhibits a smooth and continuous spectrum at any given color temperature. Therefore, there remain doubts on the appropriateness of using color rendering index to quantify the quality of lighting sources. To replace it, this study presents a new concept: spectral resemblance with respect to the blackbody-radiation, along with a new index that the quality be determined by comparing the entire spectrum directly against its natural light counterpart from human eyes’ perspective rather than machine-detected intensity. The new indicator may help resolve the dilemma as the traditional color rendering index is adopted as the light quality indicator. In this study, we demonstrate a 2,000 K dusk hue-style OLED with a 92 spectral resemblance with respect to the blackbody-radiation and a 92 color rendering index by incorporating double carrier regulating layers. According to the using spectral simulation method and device structure, it also can extend to apply in any desirable color temperature pseudo-natural light OLED.