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

Yu Cheng Chen, Po Ching Kao, Sheng Yuan Chu

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)A167-A173
JournalOptics Express
Volume18
Issue number102
DOIs
Publication statusPublished - 2010 Jun 21

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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