An Indium-Free Anode for Large-Area Flexible OLEDs: Defect-Free Transparent Conductive Zinc Tin Oxide

Monica Morales-Masis*, Fabien Dauzou, Quentin Jeangros, Ali Dabirian, Herbert Lifka, Rainald Gierth, Manfred Ruske, Date Moet, Aïcha Hessler-Wyser, Christophe Ballif

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

90 Citations (Scopus)
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Flexible large-area organic light-emitting diodes (OLEDs) require highly conductive and transparent anodes for efficient and uniform light emission. Tin-doped indium oxide (ITO) is the standard anode in industry. However, due to the scarcity of indium, alternative anodes that eliminate its use are highly desired. Here an indium-free anode is developed by a combinatorial study of zinc oxide (ZnO) and tin oxide (SnO2), both composed of earth-abundant elements. The optimized Zn-Sn-O (ZTO) films have electron mobilities of up to 21 cm2 V-1 s-1, a conductivity of 245 S cm-1, and <5% absorptance in the visible range of the spectrum. The high electron mobilities and low surface roughness (<0.2 nm) are achieved by producing dense and void-free amorphous layers as confirmed by transmission electron microscopy. These ZTO layers are evaluated for OLEDs in two anode configurations: i) 10 cm2 devices with ZTO/Ag/ZTO and ii) 41 cm2 devices with ZTO plus a metal grid. The ZTO layers are compatible with OLED processing steps and large-area white OLEDs fabricated with the ZTO/grid anode show better performance than those with ITO/grid anodes. These results confirm that ZTO has the potential as an In-free and Earth-abundant alternative to ITO for large-area flexible OLEDs.

Original languageEnglish
Pages (from-to)384-392
Number of pages9
JournalAdvanced functional materials
Issue number3
Publication statusPublished - 20 Jan 2016
Externally publishedYes


  • flexible OLEDs
  • indium-free transparent electrodes
  • large-area white OLEDs
  • TEM
  • transparent conductive oxides


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