Double-Layer Structured WPLEDs Based on Three Primary RGB Luminescent Polymers: Toward High Luminous Efficiency, Color Purity, and Stability

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• 作者：Yi Zhou ; Qingjiang Sun ; Zhan'ao Tan ; Haizheng Zhong ; Chunhe Yang ; Yongfang Li
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：May 10, 2007
• 年：2007
• 卷：111
• 期：18
• 页码：6862 - 6867
• 全文大小：375K
• 年卷期：v.111,no.18(May 10, 2007)
• ISSN：1932-7455

文摘

Efficient white polymer light-emitting diodes (WPLEDs) were fabricated on the basis of three kinds ofluminescent polymers: poly{2-[3',5'-bis(2' '-ethylhexyloxy)benzyloxy]-1,4 phenylenevinylene}-co-poly(2-methoxy-5-(2'-ethyl-hexy loxy)-1,4-phenylene vinylene) (BE-co-MEH-PPV), red; poly(6,6'-bi-(9,9'-dihexylfluorene)-co-(9,9'-dihexylfluorene-3-thiophene-5'-yl)) (PFT), green; and poly(9,9-dioctylfluorene-2,7-diyl)(PFO), blue. In order to overcome the complicated cascade energy transfer and deep trapping process, the twonarrow band gap red and green light-emitting polymers are separated into two layers. In the bottom emissionlayer, hole-transporting material poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine (poly-TPD) andelectron-blocking material poly(N-vinylcarbazole) (PVK) were chosen to work together as binary-host;concomitantly, the novel red light-emitting polymer BE-co-MEH-PPV was employed as guest. In addition,in order to avoid phase separation in the top emission layer, two fluorene-derivative polymers PFO and PFTwere used as host and guest, respectively. Through these improvements, the resulting WPLEDs showed stablewhite light emission with a maximum luminescence efficiency of 4.4 cd/A and a maximum brightness of4420 cd/m² at 17 V.