Tuning of linear and nonlinear optical properties of ZnO nanostructured films by varying the alkanolamine stabilizers

Abstract

This study investigated the effect of the stabilizer used in the seed layer growth process on the linear and nonlinear optical properties. For this purpose, various stabilizers, including monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA), were used. Zinc oxide (ZnO) seed layers were synthesized using the dip-coating method on glass substrates, followed by the hydrothermal method for growing nanostructures on top of this seed layers. The smallest crystallite size and highest dislocation density were observed in the films containing TEA as an aminoalcohol (Z-TEA). The bandgap energy values were estimated to be 3.293, 3.282 and 3.288 eV for Z-MEA, Z-DEA, and Z-TEA, respectively. The Z-MEA film with the highest absorbance exhibited the highest dissipation factor (tangent or loss factor) (tans) around 400 nm. The dissipation factor values of Z-MEA, Z-DEA and Z-TEA samples were found to range from 0.02 to 0.10. The optical conductivity (sigma opt) values of all films ranged from 1013 to 1014 s-1 . The film prepared with TEA exhibited the highest transmittance and Urbach energy value. It also demonstrated the lowest optical conductivity, refractive index, and nonlinear properties. The third nonlinear (NLO) order susceptibility (chi(3)), the linear susceptibility (chi(1)), the non- linear refractive index (n2), and the static refractive index (n0) of Z-TEA film were obtained as 1.70 x 10-14, 0.10, 4.27 x 10- 13, and 1.50, respectively. The changes in the optical properties of the films showed a good correlation with the stabilizer-dependent changes in parameters such as grain size, dislocation density, viscosity and surface density.