高三线态杂多环芳烃类电子传输材料及其器件研究

Electron-transporting materials based on fused-ring aromatic hydrocarbons derivatives have been widely used in organic light-emitting diodes (OLEDs), possessing large electron-transporting mobilities (μe) and high stabilities but poor exciton confinement abilities due to their low triplet energy. In previous research, the applicant has demonstrated that, by encapsulating the anthracene core with large sterically inert groups, the exciton confinement ability of the anthracene derivatives can be improved as ETMs. But this strategy also enlarges the intermolecular distance of ETMs, unfavorable for large μe. In this project, the applicant proposes a new strategy to solve this problem, that is developing ETMs in which hetero-atom embedded polycyclic aromatic hydrocarbons (hetero-PAH) act as electron-transporting cores. On one hand, hetero-PAHs maintain the large planar structure for large μe; on the other hand, the existence of hetero-atoms promotes the triplet energy and the electron affinity, facilitating exciton confinement and electron injection. To promote the ETM performances, the hetero-PAH units, the side groups and their connection strategy will be optimized according to the theoretical calculation results. The relationships between molecular structures and properties will be analyzed, and the factors that limit the simultaneous existence of high μe（>10-3 cm2/Vs）, good exciton confinement and long-term stability will be studied. By adopting highly efficient ETMs and optimizing the emitting layers, OLEDs devices will be fabricated for high efficiencies and long lifetimes under high brightness. The relationships between the molecular properties and device performances will also be analyzed，providing theoretical basis for developing better performed ETMs.

稠环芳烃衍生物类电子传输材料（ETMs）被广泛应用于有机发光二极管（OLED）中，具有高电子迁移率（μe）及高稳定性，但受限于低的三线态（T1）能级，激子阻挡能力差。前期工作中，申请人证明采用惰性大位阻基团包覆的策略可提升蒽衍生物的激子阻挡能力，但该方法同时增大了分子间距，降低了μe。本项目中，申请人提出采用高T1能级的杂多环芳烃作为传输母核构筑ETMs的策略。一方面，杂多环芳烃保持了大平面结构有助于实现高μe；另一方面，引入杂原子可提升T1能级和电子亲和能，促进激子阻挡和电子注入。拟结合量化计算，优化杂多环芳烃母核，侧链以及键连方式来提升材料性能；分析材料构效关系，力争突破高μe（>10-3 cm2/Vs），优异激子阻挡性能以及高稳定性之间的相互制约因素。选择理想的ETMs，优化器件发光层，制备高亮度下高效稳定的OLED器件，探索材料性质与器件性能的关系，为设计更高效ETMs奠定基础。

有机发光二极管（OLED）的性能瓶颈一方面在于电子注入和传输材料传输能力差导致的电子-空穴不平衡；另一方面在于发光材料难以实现高亮度下高效率和长寿命。基于此，本课题开展了三方面研究：1、开发了杂稠环芳烃的电子传输和注入材料，从微观角度-分子结构和宏观角度-分子堆积方式等方面揭示了材料结构与性能之间的关系，为新材料的开发奠定了基础。其中，基于稠环芳烃的电子传输材料构筑的深蓝光器件，在20 mA/cm2电流密度下，LT99（亮度衰减到初始亮度99%所需时间）超过140 h，为当时报道最长寿命；基于杂稠环芳烃-邻菲啰啉类电子传输材料器件性能媲美目前商业应用的活泼金属镱（Yb），且在寿命方面展现出优势，有望实现产业化替代；2、开发了高性能的热活化延迟荧光敏化剂材料和与之匹配的窄光谱染料，发展有机发光材料性能调控新策略，率先开发了含B-N极性键的窄光谱染料，及全光色的吲哚咔唑类染料，为多重共振分子提供了新的骨架；3、发展了磷光辅助的多重敏化的发光技术，在实现100%激子利用同时，显著缩短了激发态寿命，实现了高亮度下高效率与长寿命的OLED，在200,000cd/m2亮度下，所开发的多重敏化器件的外量子效率衰减< 10%，为超高亮度OLED应用奠定了基础。迄今为止，在本项目资助下，在国内外高水平期刊发表研究论文30篇，其中影响因子大于10的21篇，包括Chem.; Sci. Adv.; Nat. Commun.; Adv. Mater.; Angew. Chem. Int. Ed.; CCS. Chem.等。其中，2篇Angew. Chem. Int. Ed.论文被评为VIP paper；2篇论文入选杂志的封面论文；申请专利10项。参加国内外学术会议6次，做邀请报告5次。项目执行期间，申请人获得中国科协第五届青年人才托举工程项目资助和国际自然科学基金委优秀青年基金项目资助，并担任《发光学报》和《eScience》期刊的青年编委。