热激子反系间窜越荧光材料实现100%内量子效率的理论和实验探索

The electroluminescence materials are the innovation source of the OLED industry. The applicant's research starts from the molecular design of EL materials, stressing on the research on the relation between the molecular-electron structure and the EL performance, aiming at a series of high PL efficiency, high exciton utilization,high stability and low-cost electro-fluorescent materials. We developed the Donor-Acceptor material system to approach a method to percisely describe the character of Charge-transfer(CT) state, including the electron donating(or accepting) abilities, the D-A coupling strengths, the connecting patterns, the space hinderances and the environmental factors such as solvent polarities, staking and strengths of the electron-fields, and to through light upon the specific factors that influence the character of HLCT state. Next, the origin of the large energy gap of T2-T1 that sustain the "hot-exciton" method is researched in depth. The applicant researched on the structrual character and the spin-orbital coupling character(for example, the heavy-metal atom effect and the specific character of excited states, etc) of the materials with the large T2-T1 energy gap, and built up a theoretical model for the pridiction of the rates of radiactive and non-radiactive process(for example, the innersystem transfer and the intersystem cross, etc) to throw light upon the advantages of the "hot-exciton" mechanism that breakthrough the limit of radiative excitons on the higher excited state RISC channel. The research work is combined with theoritical and experimental method, and is hoping to develop a new idea on the next generation OLED material with completely independent intellectual property rights.

发光材料是有机发光二极管（OLED）的创新源头，申请者从材料的分子设计入手，重点研究发光材料分子结构、电子结构与发光性能的关系，设计优化分子结构、电子结构与激发态特征，实现高激子利用率、高发光效率、高稳定的新型廉价荧光材料设计目标。基于Donor-Acceptor（D-A）分子体系，探索准确定量描述电荷转移（CT）性质激发态的理论模型方法，探讨分子内D-A体系的给受电子能力、D/A间耦合强度、连接方式、空间位阻，以及环境因素等影响杂化局域-电荷转移（HLCT）激发态特征的规律。考察纯有机体系中构造T1-T2间大能隙的分子结构因素，以及自旋-轨道耦合强度的调节因素。建立预测辐射速率、非辐射（如系间窜越、内转换）速率的定量理论模型，揭示高能态（热）激子反系间窜越T→S提高辐射S激子比例（突破激子统计）的优越性。理论与实验结合，期望形成具有自主知识产权的新一代OLED发光材料分子设计新理念。

以高效率、低成本、新一代纯有机电致发光材料为研究目标，重点解决纯有机电致发光材料中75%三重态激子利用的关键科学问题，实现新一代有机电致发光材料的自主知识产权。从激发态性质研究入手，研究激发态电子结构特征与发光性能的关系，提出了热激子发光材料分子结构设计原理，实现了高效率、非延迟、低滚降的热激子电致发光器件。主要学术贡献为发现一种CT强度适中的特殊激发态：杂化局域-电荷转移激发态，利用其能级结构实现高能激发态间热激子反系间窜越过程，高激子利用和高光致发光效率实现高性能有机电致发光器件。具体内容包括杂化局域-电荷转移激发态的形成、电子结构特征、定量组成、分子设计、精确调控，材料表征，以及利用热激子反系间窜越实现电致发光中三重态激子利用的器件性能。项目执行期间，在Adv. Funct. Mater., Chem. Sci., Chem. Commun.等杂志发表SCI标注论文12篇，论文受到国内外同行广泛关注和积极引用评价，其中1篇论文为ESI高被引论文，3篇为杂志封面论文。