Novel P-I-N-P top-emitting organic light-emitting diodes with enhanced efficiency and stability

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• 作者：Guohua Xie ; Karsten Fehse ; Karl Leo ; Malte C. Gather
• 关键词：P-I-N-P ; Tunneling junction ; Electrical doping ; Dual-emitter ; Stability
• 刊名：Organic Electronics
• 出版年：2013
• 出版时间：September, 2013
• 年：2013
• 卷：14
• 期：9
• 页码：2331-2340
• 全文大小：2916 K

文摘

An additional p-doping layer is added to the P-I-N stack of top-emitting organic light-emitting diodes (TEOLEDs) to control the electron tunneling current and improve interfacial stability. In addition, double p-doped layers, which are adjacent to the bottom-anode, are introduced to simultaneously optimize robustness and doping efficiency of p-type doping. In the emissive layer (EML), a second assistant emitter molecule is used which transfer its triplet energy to the actual emitter which is lower in energy, thus increasing the luminous efficacy. Such a co-doped dual-emitter layer is able to separate polarons and excitons and thus reduces chemical degradation. Compared to conventional P-I-N TEOLEDs, our novel P-I-N-P device shows negligible increase of driving voltage at low bias but offers significantly increased efficiencies. In addition, the P-I-N-P stack renders the electrical properties less sensitive to thickness variations and prolonged operation, which is attributed to the existence of a one-sided abrupt N-P tunneling junction beneath the top cathode contact.