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 O2 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.