Controlling optical properties of electrodes with stacked metallic thin films for polymeric light-emitting diodes and displays

Elbert Hsing En Wu, Sheng Han Li, Chieh Wei Chen, Gang Li, Zheng Xu, Yang Yang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

11 Citations (Scopus)

Abstract

A semi-transparent metallic film and a high optical absorbing film were constructed with stacking metallic films. Both films were used as cathodes for polymeric light-emitting diodes (PLEDs). The semi-transparent film was made of gold/aluminum/gold thin multilayers with its optical transparency of the device reaches as high as ∼70% in the visible region without capping layer, and the electrical sheet resistance reduces below 10 Ω/square. During illumination of the PLED, there was approximately 47 % of light emitting from the top of the cathode surface, and 53% of light from the ITO side. The high optical absorbing film, also refer to as the black cathode, was constructed with four alternating layers of aluminum-silver, each aluminum or silver layer is 4 nm thick. The PLED with this black cathode demonstrated 126% enhancement of contrast under 1000 lx ambient illumination. The physical properties of these two cathodes were characterized by current-voltage measurement and atomic force microscopy. Ultraviolet-visible transmission spectroscopy and X-ray photoemission spectroscopy were also used to characterize the semi-transparent cathode and the black cathode respectively. For polymer light-emitting device, it is believed that morphology modification at each interface of the cathode plays a crucial role in determining the optical properties and conductivity of the over cathode.
Original languageEnglish
Pages (from-to)105-111
Number of pages7
JournalIEEE/OSA Journal of Display Technology
Volume1
Issue number1
DOIs
Publication statusPublished - 1 Sep 2005
Externally publishedYes

Keywords

  • Organic displays
  • Organic electronics
  • Organic light-emitting diode (OLED)
  • Transparent conductor

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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