Micro multi-nozzle jet coating of organic thin film for organic light-emitting diode lighting devices

Uniform deposition across large areas of an organic layer is one of the challenges for the industrial application of solution-based organic light‐emitting diode (OLED). In this paper, we propose an organic thin film deposition method for OLED using a micro multi-nozzle jet coating process. The developed micro multi-nozzle jet head consists of eighteen nozzles (100 μm diameter), a side suction line, inlets, and a nozzle protection outer hole. To demonstrate organic thin film deposition for OLED lighting device fabrication, a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) solution was used as a hole injection layer (HIL). Thickness uniformity of the PEDOT:PSS thin film was analyzed by regulating the jetting pressure. Through single-path coating of twelve successive stable column-jet flows, PEDOT:PSS organic film of 26 mm width was coated on an ITO substrate at 1 m/s head speed. The PEDOT:PSS thin film of 24.25 ± 1.55 nm (CV = 6.39%) thickness was obtained by the proposed coating method. For the feasibility test, OLED lighting devices with emission areas of 20 mm × 20 mm and 70 mm × 70 mm were successfully fabricated using PEDOT:PSS films deposited by a micro multi-nozzle jet coating method.