全树枝状磷光分子简单混合构筑发光层的白光有机电致发光器件

White organic light-emitting diodes (WOLED) are drawing more and more research attentions due to their practical applications as flat-panel displays and solid-state semiconducting lighting sources. However, the power efficiencies of most WOLEDs are still lower than what is needed for applications. Therefore, it is desired to develop novel light-emitting materials and to create simple and effective device architectures to finally improve WOLED performance. In present project, a new WOLED preparation method is proposed. First, a series of dendritic iridium complexes of different generations are designed and synthesized, among which the blue-emitting iridium complexes have m-CP dendrons with high triplet energy, and the green-, orange- and red-emitting iridium complexes have same oligo-carbazole dendrons. Second, the single-emitting-layer WOLEDs are fabricated by spin coating the mixed solution of the three primary color dendritic iridium phosphors or two complementary color ones. The emissive components will be properly selected to reach an ideal combination in terms of emitting color and dendron generations. The white light performance including color CIE coordinates and emission efficiencies are optimized by simply tuning the blending ratios. The present WOLED fabrication strategy has the following merits. (1) The WOLED configuration and fabrication method are much simple since no extra host material is necessary due to the utilization of the "self-host" dendritic emitters. (2) No phase seperation and thus high device stability are expected since all dendirtic molecules in emitting layer have same carbazole groups in molecular periphery, which is similar to the uniform film formed by same molecules. (3) The white color quality of the WOLEDs can be easily tuned by adjusting the blending ratios of the emitting components. (4) High white emission efficiencies are expected due to the phosphors nature of all emitting components. This is the first time to propose such a new WOLED preparation stragey of "total-phosphors WOLED made by simply blending dendritic iridium complexes".

白光有机电致发光器件（WOLED）由于被誉为下一代最有竞争力的平板显示器和最理想的半导体照明光源而成为近年来的研究热点。我们针对目前WOLED的效率尚不能达到实用要求的现状以及制备WOLED的各种传统方法的优缺点，提出制备"全树枝状磷光分子发光层"的单发光层WOLED的设想：设计合成一系列具有"自主体"功能特点的蓝、绿、橙、红光树枝状铱配合物，其中蓝光分子选用高三重态能量的类m-CP树枝，其它长波长发光分子通用低聚咔唑树枝，并将三原色或两种互补色的树枝状磷光分子简单混合旋涂，制备全树枝状磷光分子构成单发光层的WOLED。如此设计的白光OLEDs具有不再需要额外的主体材料、发光层内所有分子具有相同的分子外围而不容易出现相分离、调节树枝状分子的混合比例即可轻松优化白光颜色等优势。该研究提出了制备WOLED的新途径，首次尝试全树枝状磷光分子构筑发光层制备WOLED的新方法，并预期获得高效率白光。

（1）首先按照项目计划开展工作，完成了预期的红绿蓝树枝状铱配合物发光材料的合成及性质研究，以这些树枝状铱配合物为发光体制备了各自的单色光OLED器件，并以红绿蓝树枝状分子共同制备单发光层白光OLED器件，成功获得了白光，实现了由全树枝状铱配合物磷光材料制备白光器件的这一新方法，但是美中不足的是这种白光器件的效率不够理想，究其原因是溶液加工技术不能获得高质量薄膜所致，这是OLED领域内的共性问题；（2）其次，在借鉴以上树枝状铱配合物磷光材料的优缺点基础上，研制了具有高发光效率、结构新颖的小分子铱配合物磷光材料，由其制备的绿光OLED器件获得了突出的高效率；（3）进一步，热致延迟荧光（TADF）材料已成为近年OLED领域的最大研究热门，根据这一最新趋势，对项目内容进行拓展，开发了新型的TADF发光材料和适用于TADF发光客体的新型有机主体材料，并利用TADF材料制备不同结构类型（全磷光、荧光/磷光杂化）的白光OLED器件，都获得了优异的白光数据。该项目所得成果在ACS Appl. Mater. Interfaces, J. Mater. Chem. C, Chemistry-An Asian Journal, Adv. Optical Mater., Chem. Sci.等高水平SCI期刊上发表学术论文超过20篇，另有发明专利、会议论文、硕士博士学位论文等成果10项，且后续研究成果将会在接下来的一两年内不断发表出来。总之，至今已圆满完成了项目任务，实现了项目目标。