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Energy Express

  • Editor: Bernard Kippelen
  • Vol. 18, Iss. S2 — Jun. 21, 2010
  • pp: A167–A173

UV-ozone-treated ultra-thin NaF film as anode buffer layer on organic light emitting devices

Yu-Cheng Chen, Po-Ching Kao, and Sheng-Yuan Chu  »View Author Affiliations

Optics Express, Vol. 18, Issue S2, pp. A167-A173 (2010)

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An ultra-thin NaF film was thermally deposited between ITO and NPB as the buffer layer and then treated with the ultraviolet (UV) ozone, in the fabrication of organic light emitting diodes (ITO/NaF/NPB/Alq3/LiF/Al) to study its effect on hole-injection properties. The treatment drastically transforms the role of NaF film from hole-blocking to hole-injecting. This transformation is elucidated using hole-only devices, energy band measurement, surface energy, surface polarity, and X-ray photoelectron spectra. With the optimal thickness (3 nm) of the UV-ozone-treated NaF layer, the device performance is significantly improved, with a turn-on voltage, maximum luminance, and maximum current efficiency of 2.5 V, 15700 cd/m2, and 4.9 cd/A, respectively. Results show that NaF film is not only a hole-blocking layer, but also a promising hole-injecting layer after UV-ozone treatment.

© 2010 OSA

OCIS Codes
(160.4890) Materials : Organic materials
(230.3670) Optical devices : Light-emitting diodes
(230.4170) Optical devices : Multilayers

ToC Category:
Light-Emitting Diodes

Original Manuscript: February 10, 2010
Revised Manuscript: May 7, 2010
Manuscript Accepted: May 7, 2010
Published: May 26, 2010

Yu-Cheng Chen, Po-Ching Kao, and Sheng-Yuan Chu, "UV-ozone-treated ultra-thin NaF film as anode buffer layer on organic light emitting devices," Opt. Express 18, A167-A173 (2010)

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