Molecular orientation, thermal behavior and density of electron and hole transport layers and the implication on device performance for OLEDs

Kenneth L. Kearns; Hong-Yeop Na; Robert D. Froese; Sukrit Mukhopadhyay; Hunter Woodward; Dean Welsh; Timothy De Vries; David Devore; Peter Trefonas; Liang Hong

doi:10.1117/12.2062991

8 October 2014 Molecular orientation, thermal behavior and density of electron and hole transport layers and the implication on device performance for OLEDs

Kenneth L. Kearns, Hong-Yeop Na, Robert D. Froese, Sukrit Mukhopadhyay, Hunter Woodward, Dean Welsh, Timothy De Vries, David Devore, Peter Trefonas, Liang Hong

Author Affiliations +

Proceedings Volume 9183, Organic Light Emitting Materials and Devices XVIII; 91830F (2014) https://doi.org/10.1117/12.2062991
Event: SPIE Organic Photonics + Electronics, 2014, San Diego, California, United States

Abstract

Recent progress has shown that molecular orientation in vapor-deposited glasses can affect device performance. The deposition process can result in films where the molecular axis of the glass material is preferentially ordered to lie parallel to the plane of the substrate. Here, materials made within Dow’s Electronic Materials business showed enhanced performance when the orientation of the molecules, as measured by variable angle spectroscopic ellipsometry, was oriented in a more parallel fashion as compared to other materials. For one material, the anisotropic packing was observed in the as-deposited glass and was isotropic for solution-cast and annealed films. In addition, the density of an as-deposited N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)-2,2′-dimethylbenzidine (NPD) film was 0.8% greater than what was realized from slowly cooling the supercooled liquid. This enhanced density indicated that vapor-deposited molecules were packing more closely in addition to being anisotropic. Finally, upon heating the NPD film into the supercooled liquid state, both the density and anisotropic packing of the as-deposited glass was lost.

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Kenneth L. Kearns, Hong-Yeop Na, Robert D. Froese, Sukrit Mukhopadhyay, Hunter Woodward, Dean Welsh, Timothy De Vries, David Devore, Peter Trefonas, and Liang Hong "Molecular orientation, thermal behavior and density of electron and hole transport layers and the implication on device performance for OLEDs", Proc. SPIE 9183, Organic Light Emitting Materials and Devices XVIII, 91830F (8 October 2014); https://doi.org/10.1117/12.2062991

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