Structural and optical comparison of ZnS and MgF2 thin films prepared by pulsed laser ablation in liquid (PLAL) and drop casting

This work presents a comparative study of MgF₂ and ZnS single-layer antireflective coatings (ARCs) deposited on glass substrates by pulsed laser ablation in liquid (PLAL) and drop casting. Structural analysis revealed that PLAL-deposited films exhibit improved crystallinity for MgF₂ and smoother, more homogeneous surface morphology for both materials. Optical characterization showed higher transmittance and lower reflectance in PLAL coatings compared to those prepared by drop casting. The influence of PLAL on crystallite size was found to be material-dependent: it significantly reduced the crystallite size of ZnS (10.98 nm vs. 25.077 nm by drop casting) but produced a slightly larger crystallite size in MgF₂ (19.33 nm vs. 18.116 nm). In addition to the single-layer comparison, double-layer and multilayer MgF₂/ZnS-based ARCs were fabricated exclusively using the PLAL method to highlight the scalability and superior optical performance of this technique, with multilayer structures achieving up to 98% transmittance in the visible spectrum. These findings confirm PLAL as an effective and versatile technique for fabricating high-performance antireflective coatings, while revealing that its impact on crystallite size varies with the material system.