新型蓝光有机电致磷光主体材料的设计、合成与性能研究

Previous research and development data show white phosphorescent organic light-emitting diode (PhOLED) operating lifetimes to be limited by the blue portion of the PhOLED. Therefore, a new class of non-conjugated bipolar hybrid hosts for blue PhOLEDs is being developed in which the electron transport moiety (ETM) and hole transport moiety (HTM) are covalently coupled together and the π-conjugation between the two moieties is interrupted by inserting a flexible spacer consisting of σ-bonds. These non-conjugated bipolar hybrids' triplet energies will not be constrained by the electrochemical energy gap. Molecular-level mixing across a range of ETM/HTM ratios will be achieved, which allows for adjustment of charge transport balance in PhOLEDs. The new PhOLED host materials will be designed to incorporate chemical groups that serve to suppress crystallization and exciplex formation. The energetics, phase stability, film structure, photophysical and charge transport properties of these host materials with and without blue phosphorescent dopants incorporated, and the blue PhOLEDs using these host materials will be thoroughly characterized. The information gleaned from analytical work will be used to guide further synthetic work to protect chemically weak spots in the materials. The results obtained from these studies will guide development of better device architectures and improvement of operating lifetime. Once improved stability in efficient blue PhOLEDs has been achieved, the new materials will be incorporated into several promising architectures for all-phosphor white OLEDs with high efficiency and long lifetime. The results of this project will facilitate the development of blue host materials and all-phosphor white OLEDs.

针对全磷光白光有机电致发光二极管的寿命受限于其中蓝光部分的问题，本研究将开发一类适用于蓝光有机电致磷光二极管的新型非共轭双极传输主体材料。将电子传输单元和空穴传输单元由σ-键组成的柔性间隔基团连接，可打断二者之间的π-共轭效应，使主体三线态能级不再受限于能隙宽度。通过电子和空穴传输单元在分子等级不同比例的混合，可以达到有机电致磷光二极管发光层内载流子传输的平衡。通过在主体分子设计中引入必要的化学基团，抑制主体材料结晶和激基复合物的形成。通过研究这类主体材料在掺杂和不掺杂蓝光客体条件下的能级、相稳定性、膜结构、光物理、载流子传输特性以及相应蓝光有机电致磷光器件的性能，优化改进材料结构，进而改进蓝光有机电致磷光器件的结构和改善器件寿命。通过将性能优异的主体材料用于白光器件的优化，制备高效稳定的全磷光白光有机电致发光二极管。本研究将促进蓝光主体材料和全磷光白光有机电致发光二极管的发展。

设计合成了一系列基于咔唑/苯并咪唑、咔唑/三嗪、咔唑/噁二唑、咔唑/四苯基硅及三苯胺/噁二唑的双极传输主体材料，通过引入非共轭σ键柔性链、采取不同连接方式及改变给–受体比例等调节材料的性质。系统揭示了材料的结构与其热学性质、光物理性质、电化学性质及器件性能之间的关系。开发了一系列高三线态能级、热稳定性及成膜稳定性好、能级可控的双极传输主体材料，并以这些材料为基础通过优化制备了高效的磷光及热激活延迟荧光有机电致发光器件。本项目的研究有力地推动了高性能有机电致发光主体材料及有机电致发光器件的发展。