Non-radiative recombination losses in polymer light-emitting diodes

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• 作者：M. Kuik^a ; L.J.A. Koster^a ; A.G. Dijkstra^b ; G.A.H. Wetzelaer^a ; P.W.M. Blom^a ; ^c ; ^{paul.blom@tno.nl}
• 关键词：Polymer light-emitting diodes ; Efficiency ; Non-radiative recombination ; Langevin recombination ; Shockley&ndash ; Read&ndash ; Hall recombination ; Trap-assisted recombination
• 刊名：Organic Electronics
• 出版年：2012
• 期刊代码：137_15661199
• 类别：et
• 出版时间：June, 2012
• 卷：13
• 期：6
• 页码：969-974
• 文件大小：646 K

摘要

We present a quantitative analysis of the loss of electroluminescence in light-emitting diodes (LEDs) based on poly[2-methoxy-5-(2鈥?ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) due to the combination of non-radiative trap-assisted recombination and exciton quenching at the metallic cathode. It is demonstrated that for an MEH-PPV LED the biggest efficiency loss, up to 45%, arises from extrinsic non-radiative recombination via electron traps. The loss caused by exciton quenching at the cathode proves only to be significant for devices thinner than 100 nm. Removal of electron traps by purification is expected to enhance the efficiency of polymer LEDs by more than a factor of two.