Characterization of thermal annealing of gravure printed PVK/Ir(ppy)3 organic light emitting layers

We investigated gravure printing process as a promising large area and high throughput process for organic device fabrication. In this work, nanoscale organic light emitting PVK/Ir(ppy)3 layers were formed using the gravure printing process to fabricate organic light emitting diodes (OLEDs), and roughness and morphology were controlled through thermal annealing processes. The fabricated OLED device had layer structure of glass/ITO/PEDOT:PSS/PVK + Ir(ppy)3-active layer/LiF/Al. PVK(Poly (N-vinyl carbazole)) and Ir(ppy)3 were used as the host and green-emitting dopant materials, respectively. The effect of thermal annealing process was investigated on surface roughness, morphology and crystallinity of the gravure printed organic layers. The optimum conditions were determined to be around 80 °C for the gravure printed organic layers for the given materials and device structure.