Zhou Changjiang, Xiao Shengbing, Wang Man, Jiang Wenzhe, Liu Haichao, Zhang Shitong, Yang Bing
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, China.
Institute of Theoretical Chemistry, Jilin University, Changchun, China.
Front Chem. 2019 Mar 22;7:141. doi: 10.3389/fchem.2019.00141. eCollection 2019.
Throwing light upon the structure-property relationship of the excited state properties for next-generation fluorescent materials is crucial for the organic light emitting diode (OLED) field. Herein, we designed and synthesized three donor-acceptor (D-A) structure compounds based on a strong spin orbit coupling (SOC) acceptor benzo[a, c]phenazine (DPPZ) to research on the three typical types of excited states, namely, the locally-excited (LE) dominated excited state (CZP-DPPZ), the hybridized local and charge-transfer (HLCT) state (TPA-DPPZ), and the charge-transfer (CT) dominated state with TADF characteristics (PXZ-DPPZ). A theoretical combined experimental research was adopted for the excited state properties and their regulation methods of the three compounds. Benefiting from the HLCT character, TPA-DPPZ achieves the best non-doped device performance with maximum brightness of 61,951 cd m and maximum external quantum efficiency of 3.42%, with both high photoluminescence quantum efficiency of 40.2% and high exciton utilization of 42.8%. Additionally, for the doped OLED, PXZ-DPPZ can achieve a max EQE of 9.35%, due to a suppressed triplet quenching and an enhanced SOC.
揭示下一代荧光材料激发态性质的结构-性质关系对于有机发光二极管（OLED）领域至关重要。在此，我们基于强自旋轨道耦合（SOC）受体苯并[a,c]吩嗪（DPPZ）设计并合成了三种供体-受体（D-A）结构化合物，以研究三种典型的激发态，即局域激发（LE）主导的激发态（CZP-DPPZ）、局域与电荷转移混合（HLCT）态（TPA-DPPZ）以及具有热激活延迟荧光（TADF）特性的电荷转移（CT）主导态（PXZ-DPPZ）。对这三种化合物的激发态性质及其调控方法采用了理论与实验相结合的研究。受益于HLCT特性，TPA-DPPZ实现了最佳的非掺杂器件性能，最大亮度为61951 cd/m²，最大外量子效率为3.42%，同时具有40.2%的高光致发光量子效率和42.8%的高激子利用率。此外，对于掺杂的OLED，由于三重态猝灭受到抑制且SOC增强，PXZ-DPPZ可实现9.35%的最大外量子效率。
