利用P型氧化鎳提升無機、有機發光二極體之電激發光特性

Enhanced Electroluminescence assisted by p-type nickel oxide in inorganic and organic light emitting diodes

王人毅(Jen-Yi Wang)

指導教授 ： 陳永芳

國立臺灣大學/理學院/物理研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.02511

摘要

本論文利用P型氧化鎳輔助研製兩個新穎發光元件。
我們利用P型氧化鎳與N型氧化鋅奈米線，研製以氧化鋅奈米線為基底的發光二極體。我們利用磁控濺鍍在充滿氧氣的環境下濺鍍P型氧化鎳薄膜，並在其上以水熱法製作N型氧化鋅奈米線，製作出PN異質接面。由於P型氧化鎳具有寬能隙、透明的天然特性，我們量測到了以氧化鋅奈米線為基底的發光二極體具有雙面發光的獨特性質。
在發展有機發光二極體(OLED)的過程中，如何提升OLED的使用壽命一直是被關注的焦點之ㄧ。提升使用壽命的方法之ㄧ為降低OLED的驅動電壓(turn-on voltage)。在本研究中，我們首先調配出TPD:Alq3的有機聚合物混合溶液，以旋轉塗佈的方式，在ITO玻璃(陽極)上製作出發射綠光的OLED。為了降低此OLED的驅動電壓，我們在ITO的表面利用磁控濺鍍的方式濺鍍一層很薄的p-type氧化鎳薄膜當作電洞注入層(HIT)，用以調整陽極的工作函數，降低電洞注入有機層的能障，增加電洞的注入率，預期的結果是能達到降低驅動電壓的效果。我們從比較元件的I-V曲線中能得到加了p-type氧化鎳薄膜的OLED的驅動電壓能降低5~6伏特。並且由電激發光譜中得到，加了氧化鎳薄膜的OLED在較低的外加電壓時能增強其電激發光強度。
本研究中，我們將P型氧化鎳與無機、有機的發光元件結合，來達到增強其電激發光特性的目的，相信這份研究對於高品質的光電元件的研發，有一定的幫助。

關鍵字

以氧化鋅奈米線為基底的發光二極體 ； P型氧化鎳 ； TPD:Alq3混合結構 ； 有機發光二極體 ； 電激發光 ； 水熱法 ； 射頻磁控濺鍍

並列摘要

In this study, we demonstrate that thin film p-NiO can be used to enhance electroluminescence from inorganic and organic light emitting devices.
Double side light emission devices based on p-NiO/n-ZnO nanowires heterojunctions have been fabricated on ITO substrate by radio frequency (RF) magnetron sputtering combined with hydrothermal process. The electroluminescence spectra consist of a broad visible emission band centered at 570 nm and a narrow emission band at 385 nm. According to the energy band alignment, the detected visible and UV emissions arise from defect and band edge transitions in ZnO nanowires, respectively. The unique property of the double side emission is due to the nature of the large band gap of NiO film. It provides a good opportunity for the emission of a light emitting device with different colors on the top and back sides simultaneously.
A green organic light emitting device (OLED) has been fabricated by simple and low costly spin-coating small molecular TPD:Alq3 blend under proper condition. The method is different from conventional TPD/Alq3 OLED fabrication by highly cost thermal evaporation process. To satisfy requirements of high conductivity and high transparency, an extremely thin layer of p- NiO (~10 nm) was deposited on the ITO anode as hole injection layer in green light emitting OLED, which can reduce the turn-on voltage by up to 6V and improve the hole injection efficiency and EL characteristic in TPD:Alq3 blend structure OLED at lower applied voltage .
We believe that our approach of using a high conducting and transparent thin film as hole injection layer is very useful for fabricating high efficiency optoelectronic device. It can be extended to many other semiconducting materials.

並列關鍵字

ZnO nanowire-base LED ； p-NiO ； TPD:Alq3 blend structure ； OLED ； electroluminescence ； hydrothermal method ； radio frequency magnetron sputtering

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