Ag doping-induced surface functionalization of ZnO film for enhanced molecular orientation and electrical properties

Abstract

In this study, a zinc oxide (ZnO) film doped with silver (Ag) nanoparticles is introduced and utilized as an alignment layer for liquid crystal (LC) molecules. The film was fabricated using a brush-based solution coating process, with Ag doping concentrations controlled at 0, 10, and 20 wt%. The optical transmittance of the Ag-doped ZnO films exceeded 82.9 %, demonstrating performance comparable to that of conventionally used indium-tin-oxide-coated glass, indicating their potential applicability in optoelectronic devices. Uniform LC alignment on the Ag-doped ZnO film was confirmed through polarized optical microscopy analysis, exhibiting excellent light controllability. The successful incorporation of Ag into the ZnO film was verified using X-ray photoelectron spectroscopy. Additionally, scanning electron microscopy and X-ray diffraction analyses revealed an anisotropic amorphous surface structure, attributed to the unidirectional movement of the brush hairs during coating. Ag doping in the ZnO film enhanced the polar anchoring energy of the LC layer, which is crucial for image stability. This improvement also contributed to a reduction in image sticking effects and a lower residual direct current voltage. Overall, these results demonstrate the feasibility of employing Ag-doped ZnO films as functional components in electronic devices.