Similarities and differences of alkali metal chlorides applied in organic light-emitting diodes

Zhaoyue Lü, Zhenbo Deng, Ying Hou, Haisheng Xu

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The similarities and differences of alkali metal chlorides (sodium chloride (NaCl), potassium chloride (KCl), rubidium chloride (RbCl) and cesium chloride (CsCl)) applied in organic light-emitting diodes (OLEDs) are investigated. The behavior is similar for the OLEDs with these four chlorides as electron injection layer (EIL). Their maximum luminance and efficiency at 100 mA/cm 2 are within the ranges of 18 550 ± 600 (cd/m2) with an error of 3.23% and 4.09 ± 0.15 (cd/A) within an error of 3.67%, respectively. The similar performance is due to almost identical electron injection barrier for NaCl, KCl, RbCl and CsCl as EIL. Interestingly, the properties are different for devices with chlorides inserted inside tris (8-hydroxyquinoline) aluminum at the position of 20 nm away from aluminum cathode, labeled as NaCl-, KCl-, RbCl- and CsCl- devices. The relation of luminance is CsCl- > RbCl- = KCl- > NaCl-, where > and = mean better than and the same as, respectively. And the device efficiencies are decreased from CsCl to NaCl. That is, the sort order of the efficiencies is CsCl- > RbCl- > KCl- > NaCl-. The mechanism is explained by tunneling model in terms of various energy gaps estimated by optical electronegativity of NaCl, KCl, RbCl and CsCl.

Original languageEnglish (US)
Pages (from-to)106-109
Number of pages4
JournalThin Solid Films
Volume525
DOIs
StatePublished - Dec 15 2012

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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