Oscillation Method for Uniform Formation of Solution-Processed Organic Films and Its Application to Organic Light-Emitting Devices

摘要

We propose an oscillation method of solution-processed organic film coating. This method hindered a flow of solvent with organic materials during drying process. We have applied this technique into fabrication of OLEDs. In this time, oscillation is induced using piezoelectric actuator and wetted plastic roller is used for coating the organic film. By doing this method, uniform organic film with a mean roughness of 3.8 nm was achieved. Spin-coated poly(ethylene dioxythiophene) /poly(styrene sulfonate) (PEDOT) was used for hole buffer layer. Polyvinylcarbazole (PVCz) as a hole transport material, (BND) as an electron transport material, and coumarin 6 (C6) as an emission material were used. Device structure of ITO /PEDOT (40 nm)/PVCz+BND+C6 (100 nm)/LiF (1 nm)/ Al with area of 30×30 mm~2 were tested. Emission was dramatically improved by changing the oscillation condition and uniform emission was observed at higher frequencies. This technique will be promising for large-area production and short tact time. And this method is also applicable for other fabrication methods, such as, spray method and ink-jet printing method.