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Proceedings Paper

Highly enhanced phosphorescent organic light-emitting diodes with cesium fluoride doped electron injection layer
Author(s): Jongseok Han; Yongwon Kwon; Jiho Sohn; Changhee Lee
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Paper Abstract

We systematically investigate doping effect of cesium fluoride (CsF) on the device performance of organic light-emitting diodes (OLEDs). CsF can be used as a stable n-type dopant due to its low chemical reactivity and simple deposition process. We have observed that CsF could be employed as an effective n-type dopant in thin films of 3,3'-[5'- [3-(3-Pyridinyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]bispyridine (TmPyPB) through experimental studies of optical absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS) with different doping concentration. In addition, we measured bulk resistance using impedance spectroscopy in an electron-only devices (EODs) with CsF-doped TmPyPB. As the doping ratio of the CsF increases, the current densities of EOD increase and the bulk resistances of the CsF-doped layer decrease. Owing to high electrical property of CsF-doped TmPyPB in EIL, green phosphorescent OLEDs showed significantly lower voltage and considerably enhanced efficiency. The device with 30 vol% CsF-doped TmPyPB showed power efficiency of 28.1 lm/W at 1000 cd/m2, whereas the device with pristine TmPyPB exhibited 13.8 lm/W. From these results, CsF-doped TmPyPB as EIL can reduce bulk resistance of EIL and improve the electron-injection and transport properties of electron-transport layer. Therefore, we can utilize CsF as an efficient n-type dopant in EIL of OLEDs.

Paper Details

Date Published: 22 September 2015
PDF: 6 pages
Proc. SPIE 9566, Organic Light Emitting Materials and Devices XIX, 95662E (22 September 2015); doi: 10.1117/12.2187588
Show Author Affiliations
Jongseok Han, Seoul National Univ. (Korea, Republic of)
Yongwon Kwon, Seoul National Univ. (Korea, Republic of)
Jiho Sohn, Seoul National Univ. (Korea, Republic of)
Changhee Lee, Seoul National Univ. (Korea, Republic of)


Published in SPIE Proceedings Vol. 9566:
Organic Light Emitting Materials and Devices XIX
Franky So; Chihaya Adachi; Jang-Joo Kim, Editor(s)

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