突破自旋统计极限的有机分子电致荧光的理论研究

项目名称： 突破自旋统计极限的有机分子电致荧光的理论研究

项目编号： No.21473214

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 彭谦

作者单位： 中国科学院化学研究所

项目金额： 90万元

中文摘要： 提高激子的利用率一直是OLED发光材料创新和突破的关键。最近，反系间窜越的延迟荧光（TADF）材料和杂化局域-电荷转移（HLCT）激子材料均突破了自旋统计极限，使得电致发光的激子利用率几乎达到100%，有望成为新一代低成本高性能的OLED材料，引起了广泛关注。然而，TADF材料中，存在激子的高利用率与高辐射速率之间是自相矛盾的问题，HLCT材料发光机制不明确的问题，亟待深入研究。本项目将针对TADF和HLCT分子材料，建造分子激发态能级结构，定量计算分析各电子态之间的相互转化速率及竞争关系，揭示激发态演变途径及规律。重点解决TDDFT框架下激发态之间的非绝热耦合计算、三线态之间内转换和辐射跃迁速率计算等关键问题。通过系统分析结构性能关系，为理性设计出高激子利用率和高发光效率的OLED材料提供理论依据和思路。

中文关键词： 有机电致发光材料；自旋统计；激发态动力学；含时密度泛函理论；分子设计

英文摘要： High exciton utilization efficiency is the key criterion for a novel OLED light-emitting material to greatly superior to the traditional ones. Recently, the materials based on the thermal active delayed fluorescence (TADF) or the hybrided local charge transfer (HLCT) are not limited by the spin statistics principles and their exciton utilization efficiencies can up to 100% and are expected to developed into a low-cost and high-performance new generation OLED materials. This has attracted a lot of attention from the academic circle. However, in principles, it is impossible to get the high exciton utilization and the high radiative rate at the same time for TADF materials. Besides, the HLCT luminescent mechanics is unclear at present. All the issues need to be more deeply explored. Therefore, in the project, we will chose TADF and HLCT-based materials, and firstly construct the energy level structures of the molecular high excited states, and quantitatively calculate the transition rates between the related electronic singlet/triplet states, and then reveal the excited-state decay paths. We will focus on sovling the following key scientific issues: the calculation of adiabatic electronic coupling matrix between excited states in the framework of TDDFT, and the internal conversion rate and the radiative decay rate between the triplet states. In the end, by systematically analysizing the relationship between structure and property. we expect to provid the theoretical basises for the rational design of the OLED materials with high excition utilization efficiency and high lumienscence efficiency.

英文关键词： organic electroluminescence materials;spin statistics;excited-state dynamics;time-dependent DFT;molecular design