Optical limiting properties of hybrid nickel naphthalocyanine-titania nanoparticals thin films

In this work, an ultrathin nanocomposite films containing tetracarboxylic Nickel (Ⅱ) naphthalocyanine (NiNc) and titania nanoparticles are fabricated through electrostatic self-assembled layer-by-layer (LBL) technique. UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) are utilized to characterize the film. The optical limiting properties of the composite films are investigated through intensity-dependent transmittance measurements at 600 nm with 18 ps laser pulses. The results show that the composite films have notable optical limiting response (β ∼ 5.4 × 10⁻⁷ m/W), which is strongly enhanced compared to both TiO₂ and NiNc-only samples. Our results suggest that the nanocomposite films possess the potential for optical limiting applications in the phototherapeutic window.