HIGH EFFICIENCY ORGANIC LIGHT EMITTING DEVICES DEVELOPED BY FRESNAL'S THEORY

利用菲涅耳波动光学理论对有机电致发光器件的光学性质进行了研究，研制出了非常高效的深蓝白光发光材料。主要研究成果如下：1.在由染料掺杂聚合物层和α-NPD发光层组成的器件中，研制出了一种高效的深蓝色有机电致发光器件。优化后的器件在保持CIE颜色坐标(0.15，0.07)深蓝色的同时，具有很高的外量子效率(6.0%)。2.基于侧面耦合颜色转换方法(SC3M)研制了一种高效的白色OLED，即将一层有机层的蓝色发射横向转移到相邻的橙色转换材料上。具有SC3M结构的白光OLED的外量子效率为8.9%。3.利用新开发的OLED光学模拟器对多层薄膜器件的光学行为进行了评估。结果表明，外耦合效率(ηo)强烈地依赖于有机层界面附近发射区的宽度。根据我们基于菲涅耳分析和特征矩阵的新的理论分析，在保持受限发射区的情况下，精心设计发光层时，最大效率接近35%。综上所述，基于菲涅耳分析的光学设计显著提高了蓝白光OLED的发光效率。这些结果将为下一步的研究开发非常高效的有机光源奠定基础。

We investigated on optical properties in organic light emitting devices on the basis of the wave optics by Fresnel's theory, and developed very high efficiency deep-blue and white emission. Research results are summarized as follows.1.A high-efficiency deep-blue OLED has been developed in the device consisting of dye-doped polymer layer and light-emitting α-NPD layer. The optimized device showed very high external-quantum-efficiency of 6.0% with keeping deep-blue color of CIE color coordinates (0.15,0.07).2.A high efficiency white-OLED has been developed based on a Side-Coupling-Color-Conversion-Method (SC3M), in which the blue emission from an organic layer is laterally transferred to an adjacent orange color-conversion material. A white-OLED with SC3M structure showed an external quantum efficiency of 8.9%.3.Optical behavior of multi-stacked thin film devices has been evaluated by using a newly developed optical simulator for OLEDs. It was found that the outcoupling efficiency(ηo) strongly depends on the width of the emission zone near the interface between organic layers. According to our new theoretical analysis based on the Fresnel's analysis and characteristic matrix, a maximum efficiency approaches approximately 35% when the light-emitting layer is carefully designed with keeping confined emission zone.In conclusion, the emission efficiencies of blue and white OLEDs was significantly improved by optical design based on Fresnel's analysis. These results will be utilized for the development of very high efficiency organic light source in the next research stage.