Stability under humidity, UV-light and bending of AZO films deposited by ALD on Kapton.

Aluminium doped zinc oxide (AZO) films were grown by Atomic Layer Deposition (ALD) on yellow Kapton and transparent Kapton (type CS) substrates for large area flexible transparent thermoelectric applications, which performance relies on the thermoelectric properties of the transparent AZO films. Therefore, their adhesion to Kapton, environmental and bending stability were accessed. Plasma treatment on Kapton substrates improved films adhesion, reduced cracks formation, and enhanced electrical resistance stability over time, of importance for long term thermoelectric applications in external environment. While exposure to UV light intensity caused the films electrical resistance to vary, and therefore their maximum power density outputs (0.3-0.4 mW/cm3) for a constant temperature difference (∼10 °C), humidity exposure and consecutive bending up to a curvature radius above the critical one (∼18 mm) not. Testing whether the films can benefit from encapsulation revealed that this can provide extra bending stability and prevent contacts deterioration in the long term.

Roll-to-roll atmospheric plasma treatment: a green and efficient process to improve the hydrophilicity of a PET surface.

Poly(ethylene terephthalate) (PET) fibers are widely used in various fields owing to their good physical properties and chemical resistance, but PET hydrophobicity heavily compromises its use in many applications. Wet-chemical treatments are often required to induce hydrophilicity, but these can damage the polymer matrix and produce large volumes of liquid wastes. Atmospheric-pressure glow-discharge plasma (APGDP) is an alternative and ecofriendly method to obtain similar or better results with polymeric materials, compared to wet-chemical treatments. The hydrophilic behavior of PET samples is investigated after a roll-to-roll APGDP treatment by varying the plasma gas mixture, gas fluxes, and electrode temperatures. The reactive species formed in the plasma chamber are characterized by optical emission spectroscopy. The induced surface functionalization and roughness are characterized by contact-angle measurements, atomic force microscopy, and UV/Vis absorbance of a probe dye.