LiF修饰阴极的双层有机电致发光器件的延时效应  

Study on Electroluminescent Delay Time in Bilayer Organic Light-emitting Diodes with LiF/Ag Cathode

作　　者：王俊西[1] 李宏建[1,2] 熊志勇[1] 徐仁伯[2] 李雪勇[2] 

机构地区：[1]中南大学物理科学与技术学院,湖南长沙410083 [2]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《发光学报》2010年第1期17-24,共8页Chinese Journal of Luminescence

基　　金：湖南省杰出青年科学基金(03JJY1008);中国博士后科学基金(2004035083);湖南省自然科学基金(05JJ20034);中南大学科学基金(0601059)资助项目

摘　　要：基于载流子的注入、传输和复合过程,建立了双层有机发光器件的电致发光延时理论模型;讨论了电致发光延时随电压、注入势垒、内界面势垒、阳极区厚度及LiF缓冲层(BL)厚度的变化关系。结果表明:(1)低电压下,EL延时由复合过程主导,而高电压下,输运过程起着更重要的作用;(2)当δe/δh<2时,M/O界面属于欧姆接触,电流是空间电荷限制的,注入势垒的变化对复合时间trec影响较大,当δe/δh>2时,M/O界面成为接触限制,注入势垒的变化对trec几乎没有影响;(3)当内界面势垒超过0.3eV,H′h对trec的影响明显变弱,复合延迟时间基本上由电压和其它因素控制;(4)当电压较小时,随Lh/L的增大,trec增大;当电压超过某一值后,trec几乎不随Lh/L的变化而变化;(5)对于LiF/Ag阴极,在不同的偏压下,LiF的厚度在3.1nm左右时的复合时间最短,对应的EL延迟时间也最短,这与实验中从电致发光效率的角度得出的LiF最佳厚度一致。Based on the mechanism of injection, transport and recombination of the charge carriers, a model was developed to calculate the delay time of electroluminescence （EL） from bilayer organic light-emitting diodes. The relations of the recombination delay time versus the applied voltage and injection barrier or internal interfacial barrier or the thickness of organic layer were revealed. The optimal thickness of inserted LiF in bilayer organic light-emitting devices was calculated. The results shown that： （ 1 ） the EL delay time is dominated by recombination process at lower applied voltage and transport process at higher applied voltage; （2） when δc/δh〈2 〈 2, metal/organic （M/O） interface is ohmic contact, whenδc/δh〈2 〉 2, M/O becomes contact limited; （ 3 ） when the potential of internal interface barrier exceeds 0.3 eV, the effect of Hh＇ on trec becomes very weak and trec is fundamentally governed by the applied voltage or other factors; （4） when increasing Ls/L, tree has a rising trend at low voltage. When the applied voltage exceeds a threshold value, trec does not change with Lh/L; （5） considering OLEDs with LiF/Ag cathode on different applied voltage, when Ld ≈ 3.1 nm, both of the recombination time and the electroluminescent delay time are the shortest.

关 键 词：电致发光延时 注入势垒 内界面势垒 LiF修饰 

分 类 号：TN383.1[电子电信—物理电子学] TN873.3