Stabilized blue emission from polyfluorene-based light-emitting diodes: Elimination of fluorenone defects
Stabilized blue emission from polyfluorene-based light-emitting diodes: Elimination of fluorenone defects
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DOI：
10.1002/adfm.200304279
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发表时间：
2003-04-01
影响因子：
19
通讯作者：
Xiao, SS
中科院分区：
文献类型：
--
作者：
Gong, XO;Iyer, PK;Xiao, SS
基于聚荧烯(PF)的发光二极管(LED)通常在工作状态下表现出器件退化，同时出现强烈的低能量发射带(类似于2.2-2.4 eV)。这个较长的波长带将所需的蓝色发射转换为蓝绿色甚至黄色。我们研究了不同分子结构的PFS的光致发光(PL)和电致发光(EL)，发现低能发射带是由光氧化、热氧化或器件制作过程中引入的荧酮缺陷引起的。X射线光电子能谱(XPS)结果表明，钙的存在对PF的氧化有很强的催化作用。荧酮缺陷对电致发光的贡献大于对发光的贡献。利用一种新型的电子传输材料作为发射型PF和Ca/Ag(Ba/Ag)阴极之间的缓冲层，稳定了PF的蓝色电致发光。
Polyfluorene (PF)-based light-emitting diodes (LEDs) typically exhibit device degradation under operation with the emergence of a strong low energy emission band (at similar to2.2-2.4 eV). This longer wavelength band converts the desired blue emission to blue-green or even yellow. We have studied both the photoluminescence (PL) and electroluminescence (EL) of PFs with different molecular structures and found that the low-energy emission band originates from fluorenone defects which are introduced by photo-oxidization, thermal oxidation, or during device fabrication. X-ray photo-emission spectroscopy (XPS) results show that the oxidation of PF is strongly catalyzed by the presence of calcium. The fluorenone defects generate a stronger contribution to the EL than to the PL. By utilization of a novel electron-transporting material as a buffer layer between the emissive PF and the Ca/Ag (Ba/Ag) cathode, the blue EL emission from the PF was stabilized.