Enhancing optical and electrical properties of Al-doped ZnO coated polyethylene terephthalate substrates by laser annealing using overlap rate controlling strategy

Aluminum-doped zinc oxide (AZO) layers were deposited on polyethylene terephthalate (PET) flexible substrates and optimized by laser annealing using a 532 nm nanosecond pulsed laser. Effects of overlap rates, i.e. laser spot overlap rate (SOR) and laser scan line overlap rate (LOR), on AZO/PET films were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), UV-visible transmittance spectra and digital four-point probe instrument, respectively. Laser annealing could greatly enhance grain crystallinity, increase crystallite size and avoid damage to the PET flexible substrates, thus effectively enhance transmittance and conductivity of the films. The results showed that the AZO/PET film annealed by using 85% SOR and 60% LOR presented the highest average visible transmittance of 76.2% and the lowest resistivity of 1.95×10−3 Ω cm, which respectively improved by approximately 23% and 75% compared to those of the as-deposited AZO/PET film. This work may be of great importance from the viewpoint of performance optimization of transparent conductive oxide (TCO) flexible films.