Structural and optical exploration of promising zinc (8-hydroxyquinoline) thin films for wide-scale optoelectronic applications

Abstract

This research presents a detailed sequential study of the thickness effect on structural, morphological, and optical properties of vacuum thermally deposited zinc 8-hydroxyquinoline (ZnQ2) thin films. The FTIR results demonstrate that ZnQ2's molecular structure has a high degree of stabilization. On the other hand, the change in thickness affects the film's roughness. The film roughness decreases to 2.398 nm as the film thickness increase to 143 nm, and then roughness increases again at a thickness of 185 nm. The optical absorption features of the prepared films are explained. The optical energy gap has been calculated and found to be in the range of (2.79–2.87) eV. Furthermore, the refractive index dispersion has been analyzed. ZnQ2 thin film of thickness 87 nm achieved the highest linear optical susceptibility, nonlinear optical susceptibility, and nonlinear refractive index. The high peak located at photon energy 4.4 eV assures the validity of the material's proposal for optical switching applications. Besides, compared to many other organic complexes, ZnQ2 is a highly recommended candidate for efficient organic optoelectronic and optical switching applications.