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Evolution of pure hydrocarbon hosts: simpler structure, higher performance and universal application in RGB phosphorescent organic light-emitting diodes
摘要： In the field of phosphorescent organic light-emitting diodes (PhOLEDs), designing high-efficiency universal host materials for red, green and blue (RGB) phosphors has been quite a challenge. To date, most of the high-efficiency universal hosts reported incorporate heteroatoms, which have a crucial role in the device performance. However, the introduction of different kinds of heterocycles increases the design complexity and cost of the target material and also creates potential instability in the device performance. In this work, we show that pure aromatic hydrocarbon hosts designed with the 9,90-spirobifluorene scaffold are high-efficiency and versatile hosts for PhOLEDs. With external quantum efficiencies of 27.3%, 26.0% and 27.1% for RGB PhOLEDs respectively, this work not only reports the first examples of high-efficiency pure hydrocarbon materials used as hosts in RGB PhOLEDs but also the highest performance reported to date for a universal host (including heteroatom-based hosts). This work shows that the PHC design strategy is promising for the future development of the OLED industry as a high-performance and low-cost option.
关键词： RGB phosphors,PhOLEDs,external quantum efficiencies,phosphorescent organic light-emitting diodes,universal host materials,pure aromatic hydrocarbon hosts,9,90-spirobifluorene scaffold
更新于2025-09-23 15:21:01
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Spirobifluorene-based oligopyridine derivatives as electron-transporting materials for green phosphorescent organic light-emitting diodes
摘要： The electron-transporting materials (ETMs), 2,7-bis(3,5-di(pyridin-3-yl)phenyl)-9,9'-spirobi[fluorene] (3-4PySF) and 2,7-bis(3,5-di(pyridin-4-yl)phenyl)-9,9'-spirobi[fluorene] (4-4PySF) were designed and synthesized by combining spirobifluorene moiety with di(pyridine-3-yl)phenyl and di(pyridine-4-yl)phenyl, respectively. The spirobifluorene moiety improves materials’ rigid twisted structure to ensure the morphological stability of amorphous film, and pyridine acts as electron acceptor to enhance electron-transporting ability of materials. The dependence of electron-transporting property on the position of substituted pyridine rings was studied. The melting point (Tm) of 4-4PySF is estimated to be 41 ℃ higher than that of 3-4PySF. And the higher current density in the electron only devices exhibited by 4-4PySF revealed the effect of nitrogen atom position on the charge-transporting properties. Green PhOLEDs based on bis(2-phenylpyridine)iridium(III)(2,2,6,6-tetramethylheptane-3,5-diketonate) (Ir(ppy)2tmd) as the emitter and 3-4PySF, 4-4PySF and 1,3,5-tris(N-phenylbenzimidazol-2-yl-benzene (TPBi) as ETMs were fabricated. Compared to the device based on the conventional ETM TPBi, the devices based on new ETMs exhibited a higher maximum external quantum efficiency (EQE) of 20.5% and a lower turn-on voltage (Von) of 2.6 V.
关键词： electron-transporting material,intermolecular interaction,oligopyridine,organic light-emitting diode,spirobifluorene
更新于2025-09-19 17:13:59