Abstract
In optoelectronic device, transparent conducting oxide (TCO) acts as an electrode. In this work the rare earth element terbium (Tb) was doped with FTO by simple and inexpensive nebulizer spray pyrolysis (NSP) technique. Structural, optical end electrical properties were investigated for all the synthesized films. X-Ray diffraction (XRD) analysis confirmed that all the prepared films exhibited polycrystalline nature with tetragonal crystal structure and size of the crystalline reduced with increasing Tb concentration. Raman active doubly degenerate mode (Eg), IR active mode (Eu) and vibration mode (B2g) were found from Raman analysis. Atomic force microscope (AFM) images visualises the granular sized particle and the roughness of the Tb doped films. Elememental analysis spectrum exhibited Sn, O, F and Tb elements for 1.5 wt.% Tb doped thin film. Photoluminacence (PL) analysis revealed that UV, blue and green (visible) emission and UV emission intensity was reduced systamatically for the doped films. From UV–Vis analysis, highest optical transmittace were deduced for 1.5 wt.% Tb doped film. Reflectance, absorbance and band gap also been observed for the prepared films. Refractive index, extinction coefficient and dielectric constant values were decreased with increasing Tb doping concentration. High electrical conductivity and carrier concentration were measured using four probe hall effect system. Figure of merit value for the 1.5 wt.% Tb doped film is 1.5 × 10−3 Ω-1 and therefore the prepared film suits to be an electrode in optoelectronic devices.
•Highest optical transmittance was noticed for 5 wt.% Tb doped FTO thin film and the observed band gap is 3.98 eV. Optical and dielectric constants were decreased with increasing doping concentration.•Low resistivity, high carrier concentration and high figure of merit were obtained for 5 wt.% Tb doped film.•From this novel work, we could conclude that the rare earth element Tb doped FTO thin film has high electrical conductivity, high transmittance and high figure of merit which perfectly suit for optoelectronic applications.