Enhanced linear and nonlinear optical properties of poly(vinyl alcohol) films with manganese( <scp>III</scp> ) tetraphenylporphyrin chloride additive for optoelectronic applications

Abstract Polymer‐based composite materials with tunable optical properties have garnered significant attention due to their potential applications in optoelectronics and photonics. Among them, poly(vinyl alcohol) (PVA) has been extensively investigated owing to its excellent film‐forming ability, optical transparency and compatibility with functional additives. In this study, composite films were fabricated by incorporating manganese(III) tetraphenylporphyrin chloride (MnTPPCl: a metalloporphyrin complex that absorbs visible light) into a PVA matrix at concentrations of 0.05, 0.1 and 0.25 wt% via the conventional solution casting method. The films were characterized using attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, SEM and UV–visible–near infrared (NIR) spectrophotometry to examine their structural, morphological and optical properties, respectively. ATR‐FTIR analysis confirmed the successful formation of molecular interactions between MnTPPCl and PVA, facilitated by hydrogen bonding and coordination. SEM micrographs revealed a smooth surface for pure PVA, whereas the incorporation of MnTPPCl introduced uniformly distributed spherical domains whose size and density increased with the dopant concentration. Optical studies revealed a redshift in the absorption edge, accompanied by the emergence of MnTPPCl‐specific absorption bands. A decrease in the indirect optical bandgap (from 4.98 to 4.37 eV) and an increase in the absorption coefficient (up to 10 −13 cm −1 ) were observed. Furthermore, enhancements in both optical conductivity and dielectric response were recorded. Nonlinear optical measurements demonstrated a pronounced improvement, with the third‐order nonlinear susceptibility ( χ (3) ) increasing from 1 × 10 −13 to 1.2 × 10 −13 esu, and the nonlinear refractive index ( n 2 ) exhibiting a tenfold enhancement. These results demonstrate that MnTPPCl can effectively tune the structural and optical properties of PVA, making these composites promising materials for advanced optoelectronic, nonlinear optical and photonic device applications. © 2025 Society of Chemical Industry.