Performance of multifunctional antibacterial moisture barrier films with different Zn/Al ratios fabricated by plasma enhanced atomic layer deposition.

[Display omitted] • Zn-Al composite oxide-based antibacterial moisture barrier thin film was developed. • Refractive index and transmittance changed linearly with Zn ratio in the deposited film. • Films with different Zn content were highly antibacterial against E. coli and S. aureus. • Zn-Al composite oxide surface was mold-free after the mold tests. • Proposed film can be applied to functional optical films. This study investigated Zn–Al composite oxide-based antibacterial moisture barrier film for flexible electronic devices using PEALD. Diethyl zinc and trimethyl aluminium precursors were used to deposit Zn and Al atoms, respectively, which were oxidised using oxygen plasma. The transmittance, refractive index, and water vapour transmission rate (WVTR), as well as the antibacterial and antifungal properties of the Zn–Al composite oxide thin films with different Zn/Al ratios were evaluated comparatively. The deposited films exhibited a linear change in refractive index from 1.66 to 1.87 and transmittance from 87.8 to 78.3% with an increase in the Zn ratio from 24.7 to 100. Furthermore, the film with a Zn ratio of 10.4 showed the best WVTR of 9.06 × 10−4 g/m2/day. In addition, the antibacterial and antifungal properties of the Zn–Al composite oxide thin films were evaluated through antibacterial and mould growth tests, respectively. All samples exhibited high antibacterial activities of 6.2 and 4.7 against Escherichia coli and Staphylococcus aureus , respectively, and no mould growth occurred on the surfaces of the Zn–Al composite oxide films. The antibacterial moisture-barrier films developed in this study can apply such as protecting human health, next-generation flexible touch displays and functional optical films. [ABSTRACT FROM AUTHOR]