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 Â 40 OLED devices (300 Â 300 mm 2 ) was fabricated with an area of 25 Â 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.

In this paper, zinc oxide ͑ZnO͒ thin films as an antireflective ͑AR͒ coating layer have been successfully fabricated on GaAs solar cells by the sol-gel method. ZnO films were prepared chemically by spin coating the gel with an aqueous solution of zinc acetate and ethanolamine. The current-voltage measurements of the solar cells confirmed the increase of the short-circuit current induced by the AR effect. The open-circuit voltage and fill factor were also improved by the surface passivation. As a result, the conversion efficiency of the cells without an AR coating ͑8.2%͒ was significantly enhanced to 13.6%. The results indicate that the chemical deposition of ZnO was effective for the AR coating of GaAs solar cells. Additionally, we demonstrate that the cells coated with radiation resistant ZnO films exhibit less efficiency decay than the devices without such treatment. Under the maximum proton fluence of 10 13 cm −2 , the conversion efficiency decay was reduced to 69.8%, while the solar cells without ZnO films showed an efficiency decay of 83.1%.

The switching property of thin film memories with a sandwiched structure of Al/poly(2-hydroxyethyl methacrylate) (PHEMA)/ITO has been demonstrated. In terms of bistable current–voltage (I–V) characteristics, the conduction mechanisms at low and high resistance states were characterized by an ohmic behavior and the space charge limit current dominated, respectively. The resistive switching behavior was explained by the presence of the carbon filaments, which was confirmed by observing the carbon ions diffusing in the PHEMA film in time-of-flight secondary ion mass spectrometry. Our devices have high current on/off (>103), reliable switching endurance over 500 write–read–erase–read cycles, and long retention time (>104 s).

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