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

Imprint lithography has been employed as a patterning technology for the fabrication of organic light emitting diode (OLED) devices on flexible substrates. A thin PMMA layer was first spin-coated as the etching barrier on the commercial indium-tin-oxide (ITO)-coated PET substrate. The desired PMMA pattern was obtained by pressing a patterned silicon mold on to the PMMA-coated substrate. The silicon mold was coated with a fluorine-doped diamond-like carbon film for easy mold-releasing. After etching away the residual layer in O ₂ plasma, the patterned ITO arrays were fabricated by etching in oxalic acid solution and then washing in acetone. Arrays of OLED devices with a device structure of TPD/Alq₃/Bphen/LiF/Al (25 nm/30 nm/50 nm/1.5 nm/200 nm) were fabricated on the ITO anode (on PET substrate) patterned by imprint lithography. High quality OLED arrays were obtained exhibiting a turn-on voltage of 4.8 V, a maximum luminous efficiency, of 4.7 cd/A, a maximum power efficiency of 2.8 lm/W, and a maximum luminance of 30,000 cd/m².