Absence of delayed fluorescence and triplet–triplet annihilation in organic light emitting diodes with spatially orthogonal bianthracenes†,Journal of Materials Chemistry C

当前位置： X-MOL 学术 › J. Mater. Chem. C › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Absence of delayed fluorescence and triplet–triplet annihilation in organic light emitting diodes with spatially orthogonal bianthracenes†
Journal of Materials Chemistry C ( IF 5.7 ) Pub Date : 2019-01-03 00:00:00 , DOI: 10.1039/c8tc05817b
Yong-Jin Pu _{1,

2,

3,

4,

5} , Rei Satake _{3,

4,

5,

6} , Yuki Koyama _{1,

2,

3,

4,

5} , Takahiro Otomo _{3,

4,

5,

6} , Rika Hayashi _{3,

7,

8,

9,

10} , Naoki Haruta _{3,

9,

10,

11,

12} , Hiroshi Katagiri _{3,

4,

5,

6} , Daisuke Otsuki _{3,

4,

5,

6} , DaeGwi Kim _{3,

13,

14,

15} , Tohru Sato _{3,

9,

10,

11,

12}

Affiliation

Two compounds, 2-methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN), which has a single anthracene unit, and 10,10′-diphenyl-9,9'-bianthracene (PPBA), which has two spatially orthogonal anthracene units, were compared and investigated in terms of photoelectric characteristics and the reverse intersystem crossing (RISC) process in organic light emitting diodes (OLEDs). Transient electroluminescence (EL) measurements indicated large contributions of triplet–triplet annihilation (TTA) for MADN but almost no contribution of TTA for PPBA. The magnetic field dependence of EL for the two anthracene compounds was also different. The EL of MADN was sensitive to the magnetic field at high current density, but PPBA showed less dependence, which indicated the absence of the TTA process for PPBA. TD-DFT calculations revealed that PPBA has doubly degenerate lowest triplet states (T₁ and T₂) with a much lower energy than S₁, which is unfavorable for thermally activated delayed fluorescence (TADF). The near-zero ΔE_ST between highly excited states S_m≥1 and T_n>2 is favorable to RISC at a highly excited state. Oxygen quenching of photoluminescence only for PPBA and decreasing EL intensity with decreasing temperature only for PPBA support the existence of the RISC path from T_n>2 to S_m≥1. A high external quantum efficiency of 11% in blue OLEDs with PPBA was obtained, indicating that this orthogonal anthracene type of molecular design for RISC at a highly excited state would expand the material development of compounds emitting blue fluorescence for OLEDs.

中文翻译：

具有空间正交双蒽的有机发光二极管中没有延迟荧光和三重态-三重态an灭†

两种化合物，分别是具有一个蒽单元的2-甲基-9,10-双（萘-2-基）蒽（MADN）和10,10'-联苯-9,9'-联蒽（PPBA），具有两个空间正交的蒽单元，在光电特性和有机发光二极管（OLED）中的反向系统间交叉（RISC）过程方面进行了比较和研究。瞬态电致发光（EL）测量表明MADN的三重态-三重态let灭（TTA）的贡献很大，而PPBA几乎没有TTA的贡献。两种蒽化合物的EL的磁场依赖性也不同。MADN的EL在高电流密度下对磁场敏感，但PPBA的依赖性较小，这表明PPBA没有TTA流程。₁和T₂）的能量远低于S₁，这对热激活延迟荧光（TADF）不利。接近零Δ Ê _ST高激发态S之间_米≥1和T_{Ñ > 2}是有利的RISC在高度兴奋状态。仅PPBA光致发光的氧淬灭，并用仅用于PPBA降低温度降低EL强度支持从T中的RISC路径的存在_{Ñ > 2}至S_米≥1。在具有PPBA的蓝色OLED中获得了11％的高外部量子效率，这表明在高激发态的RISC正交蒽型分子设计可扩展OLED发射蓝色荧光的化合物的材料开发。

更新日期：2019-01-03

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南