Direct observations of the charge behavior of a high-efficiency blue organic light-emitting diode under operating conditions using electric-field-induced doubly resonant sum-frequency-generation vibrational spectroscopy
Direct observations of the charge behavior of a high-efficiency blue organic light-emitting diode under operating conditions using electric-field-induced doubly resonant sum-frequency-generation vibrational spectroscopy
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DOI：
10.1016/j.orgel.2019.07.008
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发表时间：
2019-11-01
影响因子：
3.2
通讯作者：
Tsutsui, Tetsuo
中科院分区：
文献类型：
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作者：
Sato, Tomoya;Miyamae, Takayuki;Tsutsui, Tetsuo
利用电场诱导双共振和频(EFI-DR-SFG)振动光谱研究了利用三重-三重湮没(TTA)现象的高效多层蓝色有机电致发光二极管(OLED)中的载流子行为。当我们对蓝色OLED施加正向或反向偏置电压时，我们观察到EFI-DR-SFG信号的增强-特别是1404、1464和1601厘米(-1)处的峰值。我们对工作的蓝色OLED中载流子行为的EFI-DR-SFG分析结果显示，1404和1464 cm(-1)处的峰值强度发生了变化，表明电子在电子阻挡层/发射层界面积累。相反，空穴传输材料的峰强度的变化是由于空穴注入层/空穴传输层界面处界面极化电荷的抵消引起的。这些结果表明，EFI-DR-SFG技术是直接研究具有复杂工作机制的实际多层有机器件中载流子行为的有力而有效的工具。
We investigated the carrier behavior in a high-efficiency multilayer blue organic light-emitting diode (OLED) that employs the triplet-triplet annihilation (TTA) phenomenon using electric-field-induced doubly resonant sum-frequency generation (EFI-DR-SFG) vibrational spectroscopy. We observed enhancements of the EFI-DR-SFG signals-particularly the peaks at 1404, 1464, and 1601 cm(-1)-when we applied forward- or reverse-bias voltages to the blue OLEDs. The results of our EFI-DR-SFG analyses of the carrier behavior in an operating blue OLED showed changes in the peak intensities at 1404 and 1464 cm(-1), indicating that the electrons accumulate at the electron-blocking layer/emission layer interface. Conversely, the changes in the intensities of the peaks obtained from the hole-transport materials are caused by the cancelation of the interfacial polarization charges at the hole-injection layer/hole-transport layer interface. These results demonstrate that the EFI-DR-SFG technique is a powerful and effective tool for directly investigating the carrier behavior in practical multilayer organic devices with complicated operating mechanisms.