荧光粉
吸热过程
磷光
放热反应
材料科学
三重态
化学
激发态
电致发光
有机发光二极管
光化学
光电子学
分子
原子物理学
物理化学
吸附
有机化学
荧光
光学
物理
图层(电子)
作者
Chihaya Adachi,Raymond C. Kwong,Peter I. Djurovich,Vadim Adamovich,Marc A. Baldo,Mark E. Thompson,Stephen R. Forrest
摘要
Intermolecular energy transfer processes typically involve an exothermic transfer of energy from a donor site to a molecule with a substantially lower-energy excited state (trap). Here, we demonstrate that an endothermic energy transfer from a molecular organic host (donor) to an organometallic phosphor (trap) can lead to highly efficient blue electroluminescence. This demonstration of endothermic transfer employs iridium(III)bis(4,6-di-fluorophenyl)-pyridinato-N,C2′)picolinate as the phosphor. Due to the comparable energy of the phosphor triplet state relative to that of the 4,4′-N,N′-dicarbazole-biphenyl conductive host molecule into which it is doped, the rapid exothermic transfer of energy from phosphor to host, and subsequent slow endothermic transfer from host back to phosphor, is clearly observed. Using this unique triplet energy transfer process, we force emission from the higher-energy, blue triplet state of the phosphor (peak wavelength of 470 nm), obtaining a very high maximum organic light-emitting device external quantum efficiency of (5.7±0.3)% and a luminous power efficiency of (6.3±0.3)lm/W.
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