Efficient sodium chlorate/calcium/aluminum cathode for polymer light-emitting diodes

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• 作者：Yufeng Hu ; Shengwei Shi ; Yanguang Zhang ; Quanguo Zhou ; Lixiang Wang ; Dongge Ma and Xinglin Li
• 关键词：Organic semiconductors ; Optoelectronic devices ; Electrical properties and measurements ; Alkali metals
• 刊名：Thin Solid Films
• 出版年：2005
• 出版时间：2005
• 年：2005
• 卷：489
• 期：1-2
• 页码：262-265
• 全文大小：148 K

文摘

A cathode system comprising an ultra thin sodium chlorate (NaCl) layer and an overlaid calcium (Ca) metal in polymer light-emitting diodes (PLEDs) based on poly[2-methoxy,5-(2-ethylhexoxy)-1,4-phenylene vinylene] is presented. It is demonstrated that introducing a thin NaCl layer further improves the brightness and electroluminescent efficiency of PLEDs. The maximum brightness and efficiency, respectively, reached 22 000 cd/m² and 3.5 lm/W for PLEDs with a 1 nm NaCl layer, which are much higher than 18 500 cd/m² and 2.0 lm/W for PLEDs with Ca cathode. The investigation of the electron injection in electron-only devices with and without a NaCl layer indicates that the introduction of the NaCl layer substantially enhances the electron injection current, which in case of PLEDs leads to the improvement of the brightness and efficiency.