ITO-free large-area top-emission organic light-emitting diode by blade coating

Hao Wen Chang, Hsin-Fei Meng*, Sheng Fu Horng, Hsiao-Wen Zan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Large-area top-emitting organic light-emitting diodes (TEOLEDs) with multi-layer structure are successfully demonstrated using the solution-processable blade coating on ITO-free substrate. The semitransparent cathode of TEOLED is composed of lithium fluoride (LiF), aluminum (Al) and silver (Ag). The composition of 3 nm Al and 10 nm Ag has a transmittance of 56% and a sheet resistance of 11 Ω/□. It is applied to the green phosphorescence device with an emissive area of 2 cm by 2.5 cm. The maximum current efficiency is 25.2 cd/A with high light-emission uniformity within 10% variation. The large-area TEOLEDs show comparable current efficiency as the small-area devices with an emissive area of 2 mm by 2 mm (having the same device structure) and better efficiency than traditional large-area bottom-emitting devices. Cesium fluoride (CsF) and n-doped electron transport layer are applied to improve electron injection. At 6 V, the luminance is raised from 141 cd/m2 to 502 cd/m2 and 304 cd/m2, respectively. In n-doped device, a simple Al/Ag cathode is used without LiF.

Original languageEnglish
Pages (from-to)19-24
Number of pages6
JournalSynthetic Metals
StatePublished - 1 Feb 2016


  • Blade coating
  • ITO-free
  • Large area
  • Organic light-emitting diode
  • Solution process
  • Top emission


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