Visualization of the internal structure of organic electronic devices in operation

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K15441
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Yamagata University
• Principal Investigator: Ohisa Satoru 山形大学, 有機材料システム研究推進本部, 客員准教授 (90646407)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 有機EL素子 / 中性子散乱 / オペランド計測 / ガラス転移

Outline of Final Research Achievements

In order to evaluate in real time how the heat generated when the organic light emitting devices is driven changes the interface structure of the organic stacked film, the device being driven is irradiated with neutrons to measure the reflectance, and at the same time, the voltage and brightness. No significant change was observed in the interface structure in the measured system. Since the operating lifetime of the measured device system was short, it was concluded that it was necessary to measure with a device system with a long lifetime. In order to easily evaluate the tendency of the interface structure to change in what kind of combination of organic stacked films, heat is applied to multiple combinations of organic stacked films, and secondary ion mass spectrometry of the laminated films is performed. The interface structure was disturbed above the glass transition temperature of the thin film, however the degree of disturbance depended on the combination of organic films.

Free Research Field

有機EL素子、中性子散乱

Academic Significance and Societal Importance of the Research Achievements

従来、有機EL素子中の薄膜の熱安定性は材料のガラス転移温度のみで議論される事がほとんどであったが、積層膜の場合はガラス転移温度だけでなく、隣接する二層膜の有機材料の組み合わせにより積層膜の熱安定性が変化する事を示唆できた。これは種々の有機積層膜を扱う有機電子デバイスの安定性を改善するためには重大な知見であると言える。