Binary Solvent Effects on Thermally Crosslinked Small Molecular Thin Films for Solution Processed Organic Light-Emitting Diodes

다국어 초록 (Multilingual Abstract)

Solution processing of crosslinkable small molecular thin films is potentially attractive for the fabrication of large-area displaypanels based on organic light-emitting diodes (OLEDs). The characteristics of a wet-processed film made of a thermallycrosslinked small-molecular material can be controlled by simply adding a cosolvent to its solution. The surface morphologyof a nanometer-scale thin film made of N4,N4′-di(naphthalen-1-yl)-N4,N4′-bis(4-vinylphenyl)biphenyl-4,4′-diamine(VNPB), dissolved in chlorobenzene, improved dramatically after the addition of 20% cyclohexanone. At the same time,better resistance of the crosslinked layer to a number of solvents frequently used in the fabrication of the adjacent emittinglayer was achieved. Moreover, the maximum current efficiency in the binary solvent device increased significantly to 22.2Cd/A, compared to 9.7 Cd/A in the reference device without VNPB, and the device lifetime was extended by up to 74.8%.
This illustrates a simple and additive-free strategy to prevent the formation of defects in solution processed thin-film stacksmade of small-molecular materials. The insights gained will be helpful in the solution-based manufacture of large-areaOLEDs and other optoelectronic components.

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