Electronic structures of organic materials and their interfaces studied by UV photoemission under very small light irradiation

微弱光照射下紫外光电子研究有机材料电子结构及其界面

• 批准号: 13640576
• 负责人: ISHII Hisao
• 金额: $ 2.05万
• 依托单位: Tohoku University (2002)Nagoya University (2001)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640576/
• 关键词: UV photoemission; sexiphenyl; organic semiconductor; Photoelectron Yield Spectroscopy; picoammeter; charging; carrier trap; ambient gas effect; 有機材料; 光電子分光; 試料帯電; イオン化エネルギー; 有機; 金属界面; 金

The detection sensitivity of UV photoemission is improved by using sensitive sub-pico ampere meter, which reduces the amount of photoelectrons emitted from sample substrate. This advantage is suited to investigate organic materials and interfaces since their conductivity is quite low and tends to make UPS measurements difficult due to sample charging. By using this technique, we investigated the electronic structure of Au/sexiphenyl(6P) interface. We found that Au cluster is formed at this interface and can work as carrier trap to leading anomalous spectral shift of UPS. Similar phenomenon probably related to interfaces charging was also found for fullerene / phthalocyanine interface which is a typical p-n junction.By using very low current measurements technique developed in the above study, we constructed measurement system of photoelectron yield spectroscopy (PYS) which is available in both ambient atmosphere and vacuum. Instead of a special ion counter used in previous works, sub-pico ammeter was used in this study with a specially-designed electrode. Signal-to-noise ration is also much improved due to wide dynamic range of the ammeter. The measurements of ionization potential of several organic semiconductors were successfully demonstrated. This technique is quite suited to investigate the properties of organic materials in atmosphere condition to discuss organic devices.

通过使用灵敏的亚皮安计，提高了紫外光发射的检测灵敏度，减少了样品衬底发射的光电子量。这一优势适合于研究有机材料和界面，因为它们的导电性相当低，而且由于样品充电，往往会使UPS测量变得困难。利用这一技术，我们研究了Au/Sexi苯基(6P)界面的电子结构。我们发现Au团簇在该界面处形成，并可作为载流子陷阱导致UPS光谱的反常漂移。对于富勒烯/酞菁界面这一典型的p-n结，我们也发现了类似的现象，可能与界面电荷有关。利用上述研究中开发的极小电流测量技术，我们构建了常压和真空下都可以使用的光电子产额谱(Pys)测量系统。本研究用亚皮安培计代替以往工作中使用的特殊离子计数器，并使用了专门设计的电极。由于电流表的宽动态范围，信噪比也得到了很大的改善。成功地测量了几种有机半导体的电离势。这项技术非常适合于在大气条件下研究有机材料的性质，以讨论有机器件。

项目成果

K.Seki: "Electronic Structure of Organic/Metal Interfaces"Thin Solid Films. 393. 298-303 (2001)

K.Seki：“有机/金属界面的电子结构”固体薄膜。

H.Ishii: "Charging and Polarization Phenomena in Thin Films and Interfaces of Organic Electronics Devices"Journal of the Institute of Electrostatics Japan. 27. 79-84 (2003)

H.Ishii：“有机电子器件薄膜和界面中的充电和极化现象”日本静电研究所杂志。