Development of Novel Light Emitting Device Consisting of C60 Polymer

有机材料具有高的荧光效率和半导体特性，有望应用于实际的电致发光器件。电致发光器件的问题之一是寿命短。为了改善这一问题，我们开发了新型的C60聚合物和共蒸发技术。对于空穴传输层(HTL)，使用了聚N-乙烯基咔唑PVCz。将香豆素6作为发光染料掺杂到PVCz中。晶胞结构为镁/三(8-喹啉)铝(III)络合物(Alq_3)/C60聚合物和PVCz/ITO。C60聚合物是一种良好的电子传输层。为了改善金属有机界面，将共蒸发技术应用于阴极的制备。在C60聚合物上制备了厚度为3 nm的镁/Alq3复合层(质量比为20：1)。新型电致发光器件的电致发光阈值略低于传统的多层电致发光器件。在整个发光区域内，发光亮度和颜色都是均匀的，直到12V的偏压才能观察到放电。这种新型电致发光器件的电流和电致发光强度分别是传统多层电致发光器件的1.4倍和2倍。这种新型电致发光器件在1000 mA/cm2的条件下显示出最高的亮度为25000cd/mm2。金属-有机共蒸发层的引入也改善了发光强度的衰减。

Organic materials have been expected to be applicable for practical electroluminescent (EL) devices because of their high fluorescence efficiency and semiconducting properties. One of problems for EL devices is short life time. In order to improve this problem we develop novel C60 polymer and co-evaporating technique. For the hole transport layr (HTL), poly (N-vinyl carbazole) PVCz was used. The coumarine 6 was doped into PVCz as an emitting dye. The cell structure was Mg/Tris (8-quinolinolate) aluminum (III) complex (Alq_3) /C60 polymer and PVCz/ITO.The all polymeric layrs were prepared by spin coating. C60 polymer works as a good electron transport layr. In order to improve the metal organic interface, the co-evaporating technique was applied to the preparation of cathode electrode. The 3 nm thick magnesium/Alq_3 composite layr (20 : 1 of weight ratio) was prepared on a C60 polymer. The EL emission threshold of novel EL device is slightly smaller than that of conventional multi-layr EL devices. Brightness and color were uniform over the whole emitting area, and no discharge was found till bias voltage of 12 V.The current and EL intensity of novel EL device is 1.4 and 2 times larger than that of conventional multi-layr EL devices, respectively. The novel EL device shows the highest brightness 25,000 cd/m^2 at the condition of 1000 mA/cm^2. The decay of the emission intensity was also improved by the introduction of co-evaporating metal-organic layr.