Emission mechanism in rubrene-doped molecular organic light-emitting diodes: Direct carrier recombination at luminescent centers
Emission mechanism in rubrene-doped molecular organic light-emitting diodes: Direct carrier recombination at luminescent centers
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DOI：
10.1109/2944.669481
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发表时间：
1998-01-01
影响因子：
4.9
通讯作者：
Kafafi, ZH
中科院分区：
文献类型：
--
作者：
Murata, H;Merritt, CD;Kafafi, ZH
本文研究了N，N '-二苯基-N，N' -双（N，N '-diphenyl-N，N' -bis）分子掺杂有机电致发光器件的发光机理以（3-甲基苯基）-1，1 '-联苯-4，4'-二胺（TPD）为主体，5，6，1,1，12-四苯基并萘（红荧烯）为掺杂剂，从能量传递和直接载流子复合两方面研究了TPD的结构，红荧烯的空穴捕获是通过单层器件中的电流与电压和迁移率测量来确定的。当电场强度大于2 × 10 ~（5）V/cm时，形成浅陷阱，并被注入的空穴填充。单层器件中观察到的电致发光表明，电子可以直接注入空穴输运体TPD。（8-羟基喹啉）铝（III）（Alq（3）），电子进入未掺杂TPD的渗透深度被确定为距离Alq（3）界面小于或等于5 nm。当掺杂红荧烯时，由于电子穿透深度的增加，发射区扩展到20 nm。这是由于电子跳跃位点从TPD向红荧烯分子的转变。在高浓度的红荧烯，电子传输发生通过跳跃的红荧烯分子。在铷掺杂的TPD中，主要的发射机制是由于掺杂剂分子中的电子-空穴复合。这是最大限度地通过红荧烯的空穴捕获和电子传输。
The emission mechanism in molecularly doped organic light-emitting diodes, where the emitting layer is composed of N,N'-diphenyl-N,N' -bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as the host and 5,6,11,12-tetraphenylnapthacene (rubrene) as the dopant, is investigated in terms of energy transfer and direct carrier recombination, Hole trapping by rubrene is identified by current versus voltage and mobility measurements in single layered devices. Shallow traps are formed and are found to be filled by injected holes at electric field above 2 x 10(5) V/cm, Electroluminescence observed in single-layered devices indicate that electrons can be injected directly into the hole transporter, TPD, In double-layered devices composed of TPD and tris-(8-hydroxyquinolinato) aluminum(III) (Alq(3)), the penetration depth of electrons into undoped TPD is determined to be less than or equal to 5 nm from the Alq(3) interface. Upon doping with rubrene, the emission zone is extended to 20 nm due to the increase in the electron penetration depth. This is attributed to the transition of the electron hopping sites from TPD to rubrene molecules. At high-rubrene concentration, electron transport occurs via hopping on the rubrene molecules. The dominant emission mechanism in rubrene-doped TPD is attributed to the electron-hole recombination at the dopant molecule. This is maximized by hole trapping and electron transport of rubrene.