TY - JOUR
T1 - An Indium-Free Anode for Large-Area Flexible OLEDs
T2 - Defect-Free Transparent Conductive Zinc Tin Oxide
AU - Morales-Masis, Monica
AU - Dauzou, Fabien
AU - Jeangros, Quentin
AU - Dabirian, Ali
AU - Lifka, Herbert
AU - Gierth, Rainald
AU - Ruske, Manfred
AU - Moet, Date
AU - Hessler-Wyser, Aïcha
AU - Ballif, Christophe
PY - 2016/1/20
Y1 - 2016/1/20
N2 - 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.
AB - 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.
KW - flexible OLEDs
KW - indium-free transparent electrodes
KW - large-area white OLEDs
KW - TEM
KW - transparent conductive oxides
UR - http://www.scopus.com/inward/record.url?scp=84959456048&partnerID=8YFLogxK
U2 - 10.1002/adfm.201503753
DO - 10.1002/adfm.201503753
M3 - Article
AN - SCOPUS:84959456048
VL - 26
SP - 384
EP - 392
JO - Advanced functional materials
JF - Advanced functional materials
SN - 1616-301X
IS - 3
ER -