Effect of seed layers on the growth of novel 3D TiO 2 nanorod thin films by Hydrothermal Method

Titanium dioxide (TiO₂) nanostructures have attracted extensive attention due to their outstanding chemical stability and potential applications in photocatalysis, optoelectronics, and energy conversion devices. In this work, TiO₂ nanorod thin films were synthesized on fluorine-doped tin oxide (FTO) coated glass substrates using a low-temperature hydrothermal method, with and without a TiO₂ seed layer deposited via spin coating. The effect of the seed layer and hydrothermal growth temperature on the structural, morphological, and optical properties of the films was systematically investigated. Hydrothermal reactions were carried out at 160°C and 170°C for 24 h. FESEM analysis reveals that the seed layer significantly enhances nucleation density and promotes the formation of uniformly distributed nanostructures, while the absence of the seed layer leads to the growth of larger and randomly oriented nanorods due to reduced nucleation sites and enhanced anisotropic crystal growth. UV–Vis spectroscopy indicates strong ultraviolet absorption with a slight red shift in the absorption edge for seed-layer-assisted films. The optical band gap values, estimated from Tauc plots, vary between 2.70 and 3.08 eV depending on synthesis conditions. Photoluminescence studies reveal defect-related emissions associated with oxygen vacancies and surface states, while reduced PL intensity in seeded samples suggests suppressed charge carrier recombination. These results demonstrate that seed-layer-assisted hydrothermal growth is an effective strategy for tailoring TiO₂ nanorod morphology and improving their optical properties for potential applications in photocatalysis and optoelectronic devices.