Mechanism of high photoluminescence quantum yield of melem
Mechanism of high photoluminescence quantum yield of melem
复制标题
密勒姆高光致发光量子产率的机理
DOI：
10.1039/d2cp03693b
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发表时间：
2022
影响因子：
3.3
通讯作者：
Kanai Kaname
中科院分区：
文献类型：
--
作者：
Kiuchi Hiroki;Sonoda Yoriko;Miyake Yuto;Kobayashi Fumiya;Tsutsumi Jun’ya;Tadokoro Makoto;Kanai Kaname
为了生产高效率的有机发光二极管，显示热激活延迟荧光（TADF）的材料作为含有重金属元素的磷光材料的替代物而引起关注。Melem是一种具有仅由氮、碳和氢组成的七嗪骨架的小分子，已知其在近紫外区域发光，并表现出高光致发光（PL）量子产率和延迟荧光。然而，高PL量子产率的机制仍然不清楚。本研究的目的是阐明高PL量子产率的机制，通过检查其详细的光学性质。当通过鼓入氧气来增加溶解氧的量时，PL量子产率和发光寿命显著降低，这表明三重态参与了发光机制。此外，PL强度的温度依赖性的研究，随着温度的降低，PL强度下降，表明它增加热。实验结果表明，TADF是一种通过从三重态到单重态激发态的上转换产生极高PL量子产率的TADF材料。
To produce high-efficiency organic light-emitting diodes, materials that exhibit thermally activated delayed fluorescence (TADF) are attracting attention as alternatives to phosphorescent materials containing heavy metallic elements. Melem, a small molecule with a heptazine backbone composed only of nitrogen, carbon, and hydrogen, is known to emit light in the near-ultraviolet region and exhibit high photoluminescence (PL) quantum yield and delayed fluorescence. However, the mechanism underlying the high PL quantum yield remains unclear. This study aimed to elucidate the mechanism of the high PL quantum yield of melem by examining its optical properties in detail. When the amount of dissolved oxygen in the melem solution was increased by bubbling oxygen through it, the PL quantum yield and emission lifetime decreased significantly, indicating that the triplet state was involved in the light-emission mechanism. Furthermore, the temperature dependence of the PL intensity of melem was investigated; the PL intensity decreased with decreasing temperature, indicating that it increases thermally. The experimental results show that melem is a TADF material that produces an extremely high PL quantum yield by upconversion from the triplet to the singlet excited state.