Diffusion at interfaces in OLEDs containing a doped phosphorescent emissive layer

McEwan, Jake A., Clulow, Andrew J., Shaw, Paul E., Nelson, Andrew, Darwish, Tamim A., Burn, Paul L. and Gentle, Ian R. (2016) Diffusion at interfaces in OLEDs containing a doped phosphorescent emissive layer. Advanced Materials Interfaces, 3 17: . doi:10.1002/admi.201600184

Author McEwan, Jake A.
Clulow, Andrew J.
Shaw, Paul E.
Nelson, Andrew
Darwish, Tamim A.
Burn, Paul L.
Gentle, Ian R.
Title Diffusion at interfaces in OLEDs containing a doped phosphorescent emissive layer
Journal name Advanced Materials Interfaces   Check publisher's open access policy
ISSN 2196-7350
Publication date 2016
Year available 2016
Sub-type Article (original research)
DOI 10.1002/admi.201600184
Open Access Status Not Open Access
Volume 3
Issue 17
Total pages 9
Place of publication Weinheim, Germany
Publisher Wiley
Collection year 2017
Language eng
Formatted abstract
A common feature of organic light-emitting diodes is their stacked multilayer structure, which is critical for efficient charge injection and transport, and light emission. In this study, it is found that a blended layer of the hole-transport material tris(4-carbazol-9-ylphenyl)amine with 6 wt% fac-tris(2-phenylpyridyl)iridium(III) [Ir(ppy)3] readily undergoes interdiffusion with adjacent layers of typical charge transport materials: bathocuproine; 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene; N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine; and N,N′-bis(naphthalen-1-yl)-N,N′-diphenylbenzidine. This process is followed using combined neutron reflectometry and in situ photoluminescence measurements. The temperature at which diffusion occurred is found to correlate with the glass transition temperature of the materials. Importantly, the layer of the material with the lowest Tg is the material that acts as a diffusive host for the adjacent layer, which has a higher Tg. That is, a high Tg material does not necessarily act as a blocking layer for diffusion. Furthermore, the results show that the order of structural change within a film can be predicted on the basis of the thermal properties of the materials. These results confirm the necessity of using materials with high glass transition temperatures throughout the device to minimize performance degradation by layer interdiffusion.
Keyword Degradation
Neutron reflectometry
Organic light-emitting diodes
Organic-organic interfaces
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Centre for Organic Photonics and Electronics
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Created: Tue, 28 Jun 2016, 10:57:15 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences