Correlation between structural, morphological, optical, and electrical features of pure and Cu, Sn, and Ti doped ZnO nanorods on FTO substrate

Undoped and Cu, Sn, and Ti doped ZnO nanorods were synthesized on FTO substrates by the hydrothermal method and systematically characterized. XRD analysis confirmed a hexagonal wurtzite structure with a strong (002) preferential orientation, indicating vertical alignment along the c-axis. While the diffraction peak position remained unchanged for undoped and Cu doped ZnO, a slight shift toward lower angles was observed for Sn and Ti doped samples, attributed to lattice expansion due to dopant incorporation. FESEM analysis revealed a systematic variation in nanorod dimensions, with both length and diameter increasing up to Sn doping and decreasing for Ti doped samples, indicating dopant-dependent growth kinetics. EDX confirmed the presence of Zn, O, and the respective dopants without secondary phases, while XPS verified successful dopant incorporation and surface chemical states. Optical studies showed a slight decrease in band gap for Cu doped ZnO and an increase for Sn and Ti doped nanorods. The PL emission exhibited a minor redshift in the 500–550 nm region, consistent with a reduction in oxygen vacancy related defect states from undoped to Ti doped samples. • We synthesize dun-doped, Cu, Sn, and Ti doped transition metal oxide (ZnO) nanorods on fluorine doped tin oxide (FTO) glass substrates using a low temperature hydrothermal method. • The crystallite size and morphology of the ZnO nanorods strongly depend on the dopant species and the ionic radius of the substitutional dopant, which govern crystal growth behaviour and crystallinity. • UV–Visible spectroscopy showed a slight reduction in the optical band gap for Cu doped ZnO nanorods compared to undoped ZnO, followed by an increase for Sn and Ti doped ZnO nanorods. • Electrical measurements demonstrated that Sn doped ZnO nanorods exhibit the highest electrical conductivity compared to undoped, Cu doped, and Ti doped ZnO nanorods.