TY - JOUR
T1 - Killer impurities in vacuum chamber that affect the lifetime of organic light-emitting diodes
AU - Fujimoto, Hiroshi
AU - Nakamura, Toshimitsu
AU - Nagayoshi, Kaori
AU - Harada, Kentaro
AU - Miyazaki, Hiroshi
AU - Kurata, Takaomi
AU - Kiyota, Junya
AU - Adachi, Chihaya
N1 - Funding Information:
This work was supported financially by the Program for Building Regional Innovation Ecosystems of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT); and was also partly supported by the International Institute for Carbon Neutral Energy Research (WPI-I2CNER) program, which is sponsored by MEXT; and by the Japan Science and Technology Agency (JST) ERATO Adachi Molecular Exciton Engineering Project under JST ERATO Grant No. JPMJER1305. We acknowledge Mr. Takeshi Nakazaki (MicroLogic Corp.) for the construction of the software for the fully automated OLED vacuum thermal evaporation system.
Publisher Copyright:
© 2020 Author(s).
PY - 2020/4/6
Y1 - 2020/4/6
N2 - We have evaluated a method to investigate killer impurities in vacuum chambers that affect the lifetimes of organic light-emitting diodes (OLEDs) processed in these chambers. In addition to chambers for the deposition of organic and metal films, an exposure chamber was installed to expose the OLEDs to impurities and residual water in a vacuum chamber during device fabrication. We studied a method to investigate the effects of these vacuum chamber impurities after establishing the reproducibility of the device lifetimes. These device lifetimes were affected by the cleanliness of the exposure chamber. Increased exposure times led to shorter device lifetimes, even if the contact angle in the exposure chamber was reduced to less than 5° using plasma cleaning. Furthermore, the device lifetime did not degrade when the partial pressure of water within the exposure chamber was reduced using a cryotrap. We were also able to evaluate the Kapton tape and vacuum greases that were used and determined whether they affected the device lifetime. These results suggest that the influence of residual water and impurities can be separated and it would then be possible to evaluate the influence of the impurities alone on the device lifetime.
AB - We have evaluated a method to investigate killer impurities in vacuum chambers that affect the lifetimes of organic light-emitting diodes (OLEDs) processed in these chambers. In addition to chambers for the deposition of organic and metal films, an exposure chamber was installed to expose the OLEDs to impurities and residual water in a vacuum chamber during device fabrication. We studied a method to investigate the effects of these vacuum chamber impurities after establishing the reproducibility of the device lifetimes. These device lifetimes were affected by the cleanliness of the exposure chamber. Increased exposure times led to shorter device lifetimes, even if the contact angle in the exposure chamber was reduced to less than 5° using plasma cleaning. Furthermore, the device lifetime did not degrade when the partial pressure of water within the exposure chamber was reduced using a cryotrap. We were also able to evaluate the Kapton tape and vacuum greases that were used and determined whether they affected the device lifetime. These results suggest that the influence of residual water and impurities can be separated and it would then be possible to evaluate the influence of the impurities alone on the device lifetime.
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U2 - 10.1063/1.5141101
DO - 10.1063/1.5141101
M3 - Article
AN - SCOPUS:85083527665
SN - 0003-6951
VL - 116
JO - Applied Physics Letters
JF - Applied Physics Letters
IS - 14
M1 - 143301
ER -