Low-dose measurement of electric potential distribution in organic light-emitting diode by phase-shifting electron holography with 3D tensor decomposition
Low-dose measurement of electric potential distribution in organic light-emitting diode by phase-shifting electron holography with 3D tensor decomposition
复制标题
利用 3D 张量分解相移电子全息技术低剂量测量有机发光二极管中的电位分布
DOI：
10.1093/jmicro/dfad019
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发表时间：
2023
期刊：
影响因子：
1.8
通讯作者：
Yoshimoto Noriyuki
中科院分区：
文献类型：
--
作者：
Sasaki Yusei;Yamamoto Kazuo;Anada Satoshi;Yoshimoto Noriyuki
为了提高有机发光二极管（OLED）的性能，了解和控制有机半导体层中的电势是必不可少的。电子全息术（EH）是用透射电子显微镜观察电势分布的一种强有力的技术。然而，它有一个严重的问题，即高能电子可能会损坏有机层，这意味着需要低剂量的EH。在这里，我们使用了一种机器学习技术，三维（3D）张量分解，去噪双层OLED的电子干涉图案（全息图），该双层OLED由N，N '-二-[（1-萘基）-N，N'-二苯基]-（1，1 '-联苯）-4，4'-二胺（α-NPD）和三-（8-羟基喹啉）铝（Alq 3）组成，在130 e−nm−2s−1的低剂量率下获得。从相位测量误差和峰值信噪比两个方面评价了去噪对全息图重构相位图像的影响。我们实现了与曝光时间长60倍的传统测量相当的精度。Alq 3层内的电场随着累积剂量的增加而减小，这表明Alq 3层因电子照射而退化。在电场退化的基础上，我们得出在不损伤OLED样品的情况下，其耐受剂量约为1.7 × 105 e −nm−2，约为常规EH的0.6倍。EH和3D张量分解去噪的组合能够进行OLED样品的时间序列测量，而不受电子照射的任何影响。
To improve the performance of organic light-emitting diodes (OLEDs), it is essential to understand and control the electric potential in the organic semiconductor layers. Electron holography (EH) is a powerful technique for visualizing the potential distribution with a transmission electron microscope. However, it has a serious issue that high-energy electrons may damage the organic layers, meaning that a low-dose EH is required. Here, we used a machine learning technique, three-dimensional (3D) tensor decomposition, to denoise electron interference patterns (holograms) of bilayer OLEDs composed ofN,N’-di-[(1-naphthyl)-N,N’-diphenyl]-(1,1’-biphenyl)-4,4’-diamine (α-NPD) and tris-(8-hydroxyquinoline)aluminum (Alq3), acquired under a low-dose rate of 130 e−nm−2s−1. The effect of denoising on the phase images reconstructed from the holograms was evaluated in terms of both the phase measurement error and the peak signal-to-noise ratio. We achieved a precision equivalent to that of a conventional measurement that had an exposure time 60 times longer. The electric field within the Alq3layer decreased as the cumulative dose increased, which indicates that the Alq3layer was degraded by the electron irradiation. On the basis of the degradation of the electric field, we concluded that the tolerance dose without damaging the OLED sample is about 1.7 × 105e−nm−2, which is about 0.6 times that of the conventional EH. The combination of EH and 3D tensor decomposition denoising is capable of making a time series measurement of an OLED sample without any effect from the electron irradiation.