The improvement in the conductive properties of thin nanoscale films of the polymer PEDOT:PSS was achieved by spraying and post-treatment of the films using methanol and formic acid that resulted in sheet resistance values in the range of 3–4 orders of magnitude higher than for the untreated films.
Roll-to-roll imprinting of two-sided structures on thermoplastic polymer film have been studied. Two continuous roll-to-roll approaches to producing structures on both sides of a web have been developed. In the sequential method, two separate printing units are used to the pattern upper and bottom surfaces of the film. In simultaneous roll-to-roll imprinting, two patterned rolls are used in one imprinting unit to pattern both sides simultaneously. In both experiments, flexible Ni-masters with submicron patterns wrapped on supporting metal rolls are used as stamps. The cellulose acetate film 95 mm thick and 50 mm wide has been used as the imprint material in the experiments. Patterned films were studied with an optical microscope and an atomic force microscope (AFM). The results indicate that both methods can be used for double-sided imprinting. However, in sequential imprinting, the first printed pattern is slightly damaged during the second printing phase.
We present a high-volume fabrication technique for making polymer lab-on-a-chip devices. Microfluidic separation devices, relying on pinched flow fraction, are roll-to-roll fabricated in a cellulose acetate (CA) film at a volume of 360 devices h−1 for a cost of approximately 0.5 euro/device. The manufacturing process consists of two steps: (i) roll-to-roll thermal nanoimprint for patterning the microchannels into a CA film and (ii) roll-to-roll lamination for bonding another CA film onto the imprinted film to seal the microchannels. Reverse gravure coating is used to apply an adhesive polymer onto the CA lid film before roll-to-roll lamination in order to increase the bonding strength. The fabricated devices are compared with planar imprinted devices with regard to the cross-sectional profile of the imprinted channels and their separation functionality. The separation functionality is characterized using fluorescent polystyrene microspheres with diameters ranging from 0.5 to 5 µm.
The core of this paper concerns the use of an amorphous transparent conductive oxide (a‐TCO), whose performance is on par with the classical indium tin oxide (ITO) films as a transparent contact in organic light emitting diodes (OLEDs). The main advantage of indium zinc oxide (IZO) films relies on their amorphous structure and high mobility that turns them likely to be used with high conductivity and high transmittance even at the infrared region. The mobility of IZO films (47.8 cm2 · V−1 · s−1) surpasses the one exhibited by ITO films (26.4 cm2 · V−1 · s−1), which along with its smoother surface and better current distribution plays an important role on OLEDs performance. Besides their similar turn‐on voltage, the devices using IZO anodes exhibit higher power efficiency than the ITO ones, which is 66, 18, and 62% for orange, green, and blue OLEDs, respectively. These results suggest that IZO can potentially be applied as an anode in full color displays based on OLEDs.
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