Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore, Singapore.
School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore, Singapore.
Angew Chem Int Ed Engl. 2018 Feb 12;57(7):1928-1932. doi: 10.1002/anie.201712104. Epub 2018 Jan 17.
Singlet-triplet conversion in organic light-emitting materials introduces non-emissive (dark) and long-lived triplet states, which represents a significant challenge in constraining the optical properties. There have been considerable attempts at separating singlets and triplets in long-chain polymers, scavenging triplets, and quenching triplets with heavy metals; nonetheless, such triplet-induced loss cannot be fully eliminated. Herein, a new strategy of crafting a periodic molecular barrier into the π-conjugated matrices of organic aromatic fluorophores is reported. The molecular barriers effectively block the singlet-to-triplet pathway, resulting in near-unity photoluminescence quantum efficiency (PLQE) of the organic fluorophores. The transient optical spectroscopy measurements confirm the absence of the triplet absorption. These studies provide a general approach to preventing the formation of dark triplet states in organic semiconductors and bring new opportunities for the development of advanced organic optics and photonics.
在有机发光材料中，单重态-三重态转换会引入非辐射（暗）和长寿命的三重态，这对限制光学性质构成了重大挑战。人们已经尝试了许多方法来分离长链聚合物中的单重态和三重态、清除三重态以及用重金属猝灭三重态；然而，这种三重态诱导的损耗不能完全消除。在此，我们报道了一种在有机芳香族荧光团的π共轭基质中构建周期性分子势垒的新策略。分子势垒有效地阻断了单重态到三重态的途径，使有机荧光团的光致发光量子效率（PLQE）接近 1。瞬态光学光谱测量证实不存在三重态吸收。这些研究为防止有机半导体中暗三重态的形成提供了一种通用方法，为先进的有机光学和光子学的发展带来了新的机遇。
