Enhanced Electron Injection Efficiency and Electroluminescence in Organic Light-Emitting Diodes by Using an Sn/Al Cathode

• 来源期刊: 中国物理快报（英文版）
• 学科: 物理学
• 年，卷（期）: 2002,（10）
• 页码范围: 1534-1536
• 页数: 3页
• 分类号: O4
• 语种: 英文

摘要

A series of organic light-emitting diodes (OLEDs) have been fabricated with different thicknesses of the tin (Sn)layer. The structure of the devices is indium-tin oxide (ITO)/copper phthalocyanine (CuPc) (12nm)/N, N'-diphenyl-N, N'-bis(1-naphthyl)-(1,1 '-biphenyl)-4, 4'-diamine (NPB) (60 nm)/tris-(8-hydroxyquinoline)aluminum(Alq3) (60nm)/Sn/aluminium (Al) (120nm). It is found that compared to OLEDs with only an Al cathode,both the electron injection efficiency and electroluminescence are improved when the thickness of the Sn layeris properly chosen. The maximum efficiency and brightness of the devices with Sn (2.1 nm)/AI and A1 cathodeare 0.54 lm/W and 9800cd/m2, and 0.261m/W and 3000 cd/m2, respectively. One possible explanation to thisphenomenon is that the enhancement of the electron density of the Sn layer due to the electron transfer from theAl to the Sn layer leads to the improvement of the electron injection efficiency and electroluminescence.