Precise pixel patterning of small molecule organic light-emitting devices by spin casting

We demonstrate the fabrication of OLEDs with precisely patterned pixels as small as 10 μm by the spin-casting of Alq3 thin films. The solution-based patterning technique produces pixels via the segregation of organic molecules into micro-fabricated channels or wells. Segregation is controlled by a combination of weak adsorbing characteristics of aliphatic terminated self-assembled monolayers and by centrifugal force, which directs the organic solution into the channel or well. This novel patterning technique may resolve the limitations of pixel resolution of the method of thermal evaporation using shadow masks, and is applicable to the fabrication of large area displays. Furthermore, the patterning technique has the potential to produce pixel sizes to the limitation of photolithography and micromachining, thereby enabling the fabrication of high-resolution micro-displays. We discuss the patterning method and device fabrication, and characterize the morphological, optical, and electrical properties of the organic pixels.

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► OLED pixels as small as 10 μm produced under spin-casting.
► Substrate pre-patterned and treated with OTS.
► PEDOT improves electroluminescence, results in uniform pixels.