Fabrication of organic light-emitting diode arrays on flexible plastic substrates by imprint lithography

Imprint lithography has been employed as a patterning technology for the fabrication of organic light-emitting diode (OLED) device arrays on flexible poly(ethylene terephthalate) (PET) substrates. Poly(methyl methacrylate) (PMMA) was used as the etching barrier coated on an indium tin oxide (ITO)/PET substrate. A silicon mold fabricated by photolithography was coated with a fluorinated diamond-like carbon film for easy mold-releasing. By hot pressing the silicon mold on the PMMA-coated ITO/PET substrate and etching in oxalic acid solution, patterned ITO strips were obtained. Imprint lithography was repeated to fabricate PMMA ribs vertical to the ITO strips. Finally, a matrix of 40 x 40 OLED devices (300 x 300 mu m(2)) was fabricated with an area of 25 x 25 mm(2) after depositing the organic and cathode layers consisting of TPD/Alq(3)/Bphen/LiF/Al. High quality OLED arrays on flexible PET substrate were obtained with a turn-on voltage of around 5 V, a luminous efficiency of 3 cd/A. a power efficiency of 1.2 lm/W, and a luminance of 800 cd/m(2) operated at 7 V on the basis of the actual light emitting area.