Lithium Hydride Doped Intermediate Connector for High-Efficiency and Long-Term Stable Tandem Organic Light-Emitting Diodes

详细信息    查看全文

• 作者：Lei Ding ; Xun Tang ; Mei-Feng Xu ; Xiao-Bo Shi ; Zhao-Kui Wang ; Liang-Sheng Liao
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：October 22, 2014
• 年：2014
• 卷：6
• 期：20
• 页码：18228-18232
• 全文大小：323K
• ISSN：1944-8252

文摘

Lithium hydride (LiH) is employed as a novel n-dopant in the intermediate connector for tandem organic light-emitting diodes (OLEDs) because of its easy coevaporation with other electron transporting materials. The tandem OLEDs with two and three electroluminescent (EL) units connected by a combination of LiH doped 8-hydroxyquinoline aluminum (Alq₃) and 1,4,5,8,9,11鈥揾exaazatriphenylene-hexacarbonitrile (HAT-CN) demonstrate approximately 2-fold and 3-fold enhancement in current efficiency, respectively. In addition, no extra voltage drop across the intermediate connector is observed. Particularly, the lifetime (T_75%) in the tandem OLED with two and three EL units is substantially improved by 3.8 times and 7.4 times, respectively. The doping effect of LiH into Alq₃, the charge injection, and transport characteristics of LiH-doped Alq₃ are further investigated by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS).

Keywords:

n-type dopant; LiH; tandem OLEDs; intermediate connector; long lifetime