Separate-coating and layer-by-layer deposition of polymer emitting materials by the spray deposition

The spray deposition method has been developed as a new way of polymer ultra-thin film preparation for organic optoelectronic devices such as an organic light emitting diode (OLED). In this method, a highly diluted solution of an organic material is nebulized into air and concentrated under a controlled evaporation condition. The resulting aerosol is transported by a carrier gas and deposited onto a solid substrate. This method has substantial advantages that an almost insoluble and non-evaporative material can be fabricated into a thin film, and that a separate-coating and layer-by-layer deposition of polymer materials can be performed. An OLED was prepared from highly diluted THF solutions (10(-4) wt%) of two poly-phenylenevinylene derivatives. One shows red emission and the other green. The red polymer was deposited on an ITO electrode through a shadow mask with round holes and 0.1 mm line width to result a fine separate-coating and the green one was laminated onto the patterned film. An Al anode was deposited on the polymer film in a vacuum evaporator. The fabricated OLED showed a patterned emission at around 10 V.