奈米型載子調制層對OLED元件之影響

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

曾俊儒

指導教授 ： 周卓煇

國立清華大學/工學院/材料科學工程學系/博士(2013年)

摘要

本研究以奈米型載子調制層研製深藍光及擬自然光有機發光二極體(organic light-emitting diodes, OLEDs)，探討載子調制層對OLED元件之影響。
在高效率深藍光OLED的研究方面，使用一螢光藍光材料2,7-bis-{2[phenyl(m-tolyl)amino]-9,9-dimethyl-fluorene-7-yl}-9,9-dimethylfluorene來製備，藉由載子調制層之數量、膜厚及位置的變化，提升元件之效率。在未使用任何載子調制層下，元件在亮度1,000 cd/m2下之能量效率為1.7 lm/W，CIE色座標為(0.143, 0.098)；當使用單層及雙層載子調制層後，能量效率由1.7提升至2.1及2.2 lm/W，元件最大亮度也由5,250提升至7,620及9,130 cd/m2，增加45%及74%。亮度之提升可歸因於載子調制層能有效地引導載子再結合於較廣的區域。此外，隨著載子調制層膜厚及位置的變化，元件之光色會有藍位移的現象。
在擬自然光OLED方面，使用六種可包圍黑體輻射曲線之色域的黑體輻射互補性染料，模擬元件光譜，並藉由雙載子調制層和多發光層元件結構設計，製備多波段擬自然光OLED。自然光在各色溫下皆呈現與黑體輻射相似之平滑且連續的光譜，一個好的人造自然光源應該直接與自然光做比較，因此，對於演色性是否為一個適當的評斷光源品質指標，則令人產生ㄧ些疑慮。為了取代演色性，本研究提出一個新的觀念指標-黑體輻射相似性，即光質應從人眼角度的亮度光譜直接與自然光比較來評斷，而非由機器偵測的能量光譜來量測。此一新指標的提出，可以解決傳統光源品質指標所遇到的困境。
本研究使用雙載子調制層製備出色溫2,000 K，演色性92，黑體輻射相似性92的超低色溫類夕陽光OLED。依光譜模擬的方法與元件結構設計，也可延伸應用至製作其他色溫之擬自然光OLED。

關鍵字

有機發光二極體 ； 載子調制層 ； 深藍光 ； 擬自然光 ； 黑體輻射相似性

並列摘要

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.

並列關鍵字

OLED ； carrier regulating layer ； deep blue ； pseudo natural light ； SRBR

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