基于咔唑的树枝状大分子紫外发光材料的制备及性能研究

Ultraviolet organic emitters have broad commercial application as a new type of UV light source owing to their advantages of contamination free, low-lost, easy large-scale production, easy integration with flexible substrates, etc. However, only a few organic molecules or polymer were reported to use as ultraviolet emitters, and their thermal stability and color purity are still questionable. This project is designed to prepare a novel carbazole-cored dendrimer ultraviolet emitter with good thermal stability and color purity. Thereinto, the structure of dendrimer can be constructed by conjugated chain or non-conjugated chain. Furthermore, the carbazole and fluorene groups would be used as terminal group to increase their fluorescence quantum efficiency. Meanwhile, the novel dendrimers were used to design and prepare devices. We would also study the dependence of luminescent characteristics on different molecular structures and composites of devices. At last, the radical motive of this project is to provide theoretical support and basic experimental data for excellent ultraviolet organic emitter.

紫外有机发光二极管作为一种新型紫外光源，具有环保、低成本、易大面积制作、易与柔性基底集成等优点，应用前景广阔。然而，目前只有少数以有机小分子或聚合物作为紫外发光材料的报道，且材料的热稳定性及色纯度普遍偏低。本项目拟选取紫外发光特性良好的咔唑类基团作为核心，通过共轭和非共轭联接方式构建树枝状大分子结构，在提高材料热稳定性同时保持高色纯度；同时，在支链末端上引入咔唑和芴等基团进一步提高材料的荧光量子效率。本项目也将基于新型树枝状大分子紫外发光材料设计制备器件，通过甄选功能基团和结合相关表征方法，系统研究树枝状大分子结构以及器件组成对材料发光特性的影响，为开发高效紫外有机发光二极管提供理论支撑和基础实验数据。

有机紫外发光二极管具有环保、低成本、易大面积制作、易与柔性基底集成等优点，可弥补传统紫外光源与新型无机半导体固态紫外光源的不足。然而关于有机紫外发光材料和有机紫外发光二极管的报道并不多。因而设计新型有机紫外发光材料将是紫外发光二极管研究的重点。本项目以咔唑为核心，合成了一系列具有高性能的紫外发光材料，并通过设计优化制备了几种结构的OLED器件。光谱分析结果表明，这系列材料表现出优越的紫外-蓝紫色发光性能（λem = 379.5 ~394.0 nm），可以获得较高的荧光量子效率（ФPL = 23 ~ 60%），具有良好的色纯度（FWHM = 40 ~ 48 nm）。通过对这类咔唑衍生物的结构进行分析发现，咔唑的9号位链上通过π键连接，如苯环的结构，由于存在共轭，材料的带隙最大，发光波长最短。通过σ键连接则带隙小，发光波长红移。最外围的取代基对光物理性能和电物理性能影响不大，对热稳定性影响很大。这对以后设计紫外发光材料的分子结构提供了帮助。