系统间交叉
电致发光
激发态
单重态
化学
有机发光二极管
三重态
光化学
自旋(空气动力学)
铱
单重态裂变
光电子学
原子物理学
材料科学
物理
热力学
生物化学
催化作用
有机化学
图层(电子)
作者
Hajime Nakanotani,Youichi Tsuchiya,Chihaya Adachi
出处
期刊:Chemistry Letters
[The Chemical Society of Japan]
日期:2021-05-05
卷期号:50 (5): 938-948
被引量:80
摘要
Harvesting excited spin-triplet states as light is essential to realize highly efficient electroluminescence (EL) in organic light-emitting devices. In recent years, thermally activated delayed fluorescence (TADF) has attracted much attention as a novel electronic transition process, since it enables harvesting electrically generated triplet energy as EL without the utilization of rare metals such as iridium and platinum. When the energy gap between the excited spin-triplet and spin-singlet states in molecules is small enough to be compared to the environmental thermal energy at room temperature, they exhibit an intense state mixing between them, resulting in highly efficient reverse intersystem crossing from the spin-triplet to the spin-singlet due to the spin allowed transition, and successive light emission as delayed fluorescence from the singlet excited-state. Using molecules exhibiting TADF, internal EL quantum efficiencies of nearly 100%, which is the theoretical limit, have been realized with sophisticated molecular design. Here, we briefly review recent developments of TADF molecules along with the current understanding of spin-flip mechanisms in purely organic molecular systems. Harvesting of excited spin-triplet is essential to realize highly efficient “bright” electroluminescence (EL) in organic light-emitting diodes. In recent years, thermally-activated delayed fluorescence (TADF) has attracted much attention as a novel electronic transition process enabling the harvesting of electrically generated excited spin-triplet as EL without the utilization of rare metals such as iridium. Using molecules exhibiting TADF, internal EL quantum efficiencies of nearly 100%, which is the theoretical limit, have been reached.
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