高效率激基缔合物发光材料的设计、合成与光电性能

Luminescent material is the core technology of organic light-emitting diode (OLED), and the excited state property essentially plays a decisive role in luminescence performance (energy, efficiency and lifetime, etc.). Based on the study of the excited state, this project focuses on the study of structure-property relationship among the dimer structures of excimer, the electronic structures of excited state and the luminescent performances, aiming to achieve a new generation of excimer emissive materials with high exciton utilization and high luminous efficiency. With the combination of theory and experiment, a systematical investigation includes the excimer formation from different pi unit, the quantitative composition and transition nature of excited state and their control factors, to establish the relationship between the dimer structure factors (such as distance, overlapping degree, the degree of pi electron delocalization, substituent, etc.), environmental factors (solvent polarity, solid aggregation, electric field, etc.) and the excimer excited state properties (energy, composition, lifetime and single-triplet energy splitting ΔEST, etc.). The dynamics of excimer excited state will be involved to discuss the nature of photophysics and photochemistry, and to develop the intermolecular and intramolecular excimer emissive materials with high efficiency using new structures and new systems, and to extend the new principles and new applications of excimer luminescence. Finally, we try to achieve the independent intellectual property rights in a new generation high-efficiency excimer light-emitting materials in terms of designs, principles and applications.

发光材料是有机发光二极管（OLED）的核心创新技术，激发态本质决定发光性能（能量、效率与寿命等），申请者从激发态研究入手，重点研究激基缔合物（excimer）发光体系的二聚体分子结构、激发态电子结构与发光性能的关系，旨在实现高激子利用、高发光效率的新一代excimer发光材料。理论与实验结合，系统研究不同π分子单元的excimer形成、激发态定量组成与结构调控因素，建立二聚体结构因素（如空间距离，重叠程度、π电子离域程度、取代基等）、环境因素（溶剂极性、固体堆积、电场等）与excimer激发态性质（能量、组成、寿命和单三重态能级劈裂ΔEST等）之间的影响规律。开展excimer激发态动力学研究，探讨光物理、光化学现象的本质原理，发展高效率分子间与分子内excimer发光的新结构与新体系，拓展excimer发光的新原理与新应用，争取新一代高效率excimer发光材料方面的自主知识产权。

通常，强分子间π-π相互作用会导致有机固体荧光猝灭。然而，在离散的π-π二聚体堆积晶体中，我们发现了一种高效率、长寿命的激基缔合物双分子荧光。理论与实验结合研究表明，这种高效率π-π堆积双分子发光主要归结于一种特殊的激发态形成：分子间杂化局域-电荷转移 (hybridized local and charge-transfer, HLCT)激发态。虽然双分子激发态导致辐射速率降低，但是这种激发态的电荷转移作用诱导分子间π-π距离减小，双分子刚性增强，更加有效地抑制了非辐射速率，最终形成高效率、长寿命双分子发光。在此基础上，我们提出了构筑离散π-π二聚体堆积结构的分子设计策略，通过π平面大小（芘、蒽、苝）可以有效调控双分子发光颜色（蓝、绿、红），发展具有自主知识产权的新一代双分子发光材料。此外，在无定型固体（薄膜和纳米粒子）中亦可实现高效率双分子发光，这些双分子发光材料将在有机发光二极管、刺激响应和生物成像等领域具有独特应用。项目执行期间，在J. Am. Chem. Soc., Adv. Funct. Mater., Chem. Commun.等杂志发表SCI标注论文12篇，中国授权专利3项，得到国内外同行积极评价和广泛关注。