Efficient organic electroluminescent devices using single-layer doped polymer thin films with bipolar carrier transport abilities
Efficient organic electroluminescent devices using single-layer doped polymer thin films with bipolar carrier transport abilities
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DOI：
10.1109/16.605468
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发表时间：
1997-12
影响因子：
3.1
通讯作者：
Chung‐Chih Wu;J. Sturm;R. Register;Jing Tian;Elena P. Dana;Mark E. Thompson
中科院分区：
文献类型：
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作者：
Chung‐Chih Wu;J. Sturm;R. Register;Jing Tian;Elena P. Dana;Mark E. Thompson
提出了由具有双极载流子传输能力的单层掺杂聚合物共混薄膜制成的电致发光器件的详细研究。活性有机层由含有分散电子传输分子的空穴传输聚合物聚（N-乙烯基咔唑）（PVK）以及不同的荧光小分子或聚合物作为发射中心以改变发射颜色组成。光致发光和电致发光（EL）特性都得到了广泛的研究。在光致发光中，可以从主体到非常稀（/spl sim/1 wt.%）量的发光材料发生非常有效的能量转移。当覆盖金属层时，发现混合薄膜的光致发光强度取决于金属覆盖的类型。系统地研究材料和器件的光学和电学特性，以了解其工作机制并优化器件。在EL中，激子似乎是在掺杂的发射中心而不是主体中形成的。我们表明，在优化的器件中，此类器件可以轻松实现相对较高的外部量子效率（>1%，仅背面发射）和较低的工作电压（超过 100 cd/m/sup 2/ 时<10 V）。研究还发现，在使用含有分散电子传输恶二唑分子的 PVK 的器件中，空气稳定性银与反应性镁银合金一样适合作为阴极接触。
Detailed studies of electroluminescent devices made from single-layer doped polymer blend thin films having bipolar carrier transport abilities are presented. The active organic layer consists of the hole-transport polymer poly(N-vinylcarbazole) (PVK) containing dispersed electron-transport molecules, as well as different fluorescent small molecules or polymers as emitting centers to vary the emission color. Both the photoluminescence and electroluminescence (EL) properties are extensively studied. In photoluminescence, very efficient transfer of energy can occur from the host to very dilute (/spl sim/1 wt.%) amounts of emitting materials. When covered with a metal layer, the intensity of photoluminescence from blend thin films was found to be dependent on the type of metal coverage. The optical and electrical properties of materials and devices were systematically studied to understand the operating mechanisms and to optimize the devices. In EL, excitons appear to be formed at doped emitting centers, rather than in the host. We show that in an optimized device, a relatively high external quantum efficiency (>1%, backside emission only) and a low operating voltage (<10 V for over 100 cd/m/sup 2/) can be easily achieved by this class of devices. It was also found air-stable Ag is as good as reactive Mg-Ag alloy for the cathode contact in devices using PVK containing dispersed electron-transport oxadiazole molecules.