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Organic light-emitting device (OLED) is becoming popular in electronic display devices. Recent attempts in the OLED field are focused on the fabrication of more efficient and reliable devices having larger panel size. To this aspect, understanding of degradation mechanism of the device in operation, especially in the chemical-state wise, is much more needed, but not yet successful. Scanning photo-electron microscopy (SPEM) is a useful tool to investigate degradation mechanism of OLED, because SPEM can directly probe chemical state information on the degraded area. Practically, however, it has been difficult to obtain chemical state information from the degraded area, because the surface of the degraded area is physically weak, becomes contaminated when exposed to air, and suffers from artifact generation in the spectral analysis due to intense x rays and electrons as probes. [1] We have developed techniques of in-situ operating the device [2] and peeling-off the photocathode layer in vacuum [3] in order to overcome the difficulty. We then have successfully obtained spectral features of strongly degraded as well as only slightly degraded area of the degraded device. I will introduce these techniques, the spectral results, and thus obtained degradation scenario of the device on operation.
[References]
1. M. C. Jung, H. J. Shin, and J. Chung, J. Appl. Phys. 101, 034907 (2007)
2. H. J. Shin, H. J. Song, J. Lee, H. J. Yoon, J. Chung, and J. C. Lee, J. Appl. Phys. 100, 084504 (2006)
3. H. J. Shin, M. C. Jung, J. Chung, K. Kim, J. C. Lee, and S. P. Lee, Appl. Phys. Lett. 89, 063503 (2006)
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