Enhancing spin-orbital coupling in deep-blue/blue TADF emitters by minimizing the distance from the heteroatoms in donors to acceptors
Enhancing spin-orbital coupling in deep-blue/blue TADF emitters by minimizing the distance from the heteroatoms in donors to acceptors
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DOI：
10.1016/j.cej.2020.127591
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发表时间：
2021-06-15
影响因子：
15.1
通讯作者：
Duan, Lian
中科院分区：
文献类型：
--
作者：
Cai, Minghan;Auffray, Morgan;Duan, Lian
如何提高深蓝/蓝色热激活延迟荧光（TADF）材料的反向系间穿越（RISC）率一直是一个亟待解决的难题。取代杂原子可以有效地增强它们的单重态和三重态之间的自旋轨道耦合（SOC），从而促进它们的RISC过程，但杂原子位置与SOC之间的关系还很少被研究。在这里，我们设计并合成了六个类似的TADF材料与不同类型和位置的杂原子。结果表明，减小给体中杂原子到受体的距离可以显著提高杂原子对单重态和三重态自然跃迁轨道的贡献，提高它们的n-p* 跃迁比例，从而提高它们之间的SOC.结果表明，含杂原子O的深蓝色TADF材料BFCZPZ 1和含杂原子S的蓝色TADF材料BTCZPZ 1的最大自旋轨道耦合矩阵元（SOCME）分别高达0.311和0.980 cm（1），这加速了它们的RISC过程。基于它们制造的深蓝/蓝色TADF器件表现出高效率和低效率滚降。这些发现为进一步设计高性能含杂原子的深蓝/蓝色TADF材料提供了指导。
How to enhance the reverse intersystem crossing (RISC) rates of deep-blue/blue thermally activated delayed fluorescent (TADF) materials remains a difficult task to be solved. Incorporating heteroatoms can effectively enhance the spin-orbital coupling (SOC) between their singlet and triplet states, and boost their RISC processes thereby, though the relationship between the locations of heteroatoms and SOC remains rarely studied. Here, we have designed and synthesized six analogous TADF materials with different types and locations of heteroatoms. It is revealed that minimizing the distance from the heteroatoms in donors to acceptors can significantly enhance the contribution of heteroatoms to the natural transition orbitals of singlet and triplet states, promote their n-p* transition proportion, and enhance the SOC between them thereby. As a result, the maximum spin-orbital coupling matrix elements (SOCMEs) of deep-blue TADF material BFCZPZ1 containing heteroatom O and blue TADF material BTCZPZ1 containing heteroatom S are as high as 0.311 and 0.980 cm (1), respectively, which accelerate their RISC processes. Fabricated deep-blue/blue TADF devices based on them exhibit high efficiencies with low efficiency roll-off. These findings provide a guideline in further designing high performance deep-blue/ blue TADF materials containing heteroatoms.