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

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 demon-strate 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.

Automated summary

This research investigates the effects of thickness on the structural, morphological, and optical properties of vacuum thermally deposited zinc 8-hydroxyquinoline (ZnQ2) thin films. The results show that ZnQ2 has a highly stable molecular structure, but the roughness of the film is affected by the thickness. The film roughness decreases until a thickness of 143 nm and then increases again at 185 nm. The optical absorption features, optical energy gap, and refractive index dispersion of the films are analyzed. The results suggest that ZnQ2 thin films with a thickness of 87 nm exhibit the highest linear optical susceptibility, nonlinear optical susceptibility, and nonlinear refractive index, making them suitable for optical switching applications.