Synthesis And Characterization Of Optical And Structural Properties Of Inorganic And Green Leaf Doped Sno Thin Films Deposited Using Spray Pyrolysis

Abstract

Dye-sensitized Nanohybrid Zn_xSn_yO_z thin films were deposited on glass substrates using spray pyrolysis method. The dye extract from the leaves of tectona grandis was used.  A concentration of 0.1M of Zn²⁺ and 1% was used respectively. Depositions were carried out at different substrate temperature of 50^oC, 100^oC, and 150^oC. The effect Zn²⁺ ion and dye extract from tectona grandis leaves on optical and solid state properties of the films were examined and analysed. The result showed that the absorbance of the undoped SnO thin films at various substrate temperatures vary from about 0.1-0.7. The absorbance generally increased with deposition/ substrate temperature exhibiting a maximum for films deposited at 150^oC. The average transmittance of both un-doped and Zn²⁺ doped SnO thin films at 350nm is above 90% regardless of the film thickness. The dye doped samples showed an improvement in optical transmission at 625nm. The reflectance spectra of all films exhibited a similar trend. Peak reflectance was observed at 350nm for un-doped and Zn²⁺ doped samples of SnO thin films while peak reflectance can be observed at 625nm for dye doped samples. It is also observed that the band gaps of the dye doped samples are lower: 1.55eV- 1.83eV than those of the Zn²⁺ doped samples: 1.60eV – 2.20eV. This showed that the incorporation of the dye shifted the fundamental absorption edge of the un-doped SnO thin films thus providing tuning effect of the band gap for device applications. The diffractograms of SnO doped Zn are characterized by relatively low intensity for all the samples irrespective of the doping concentration compared to the un-doped SnO samples. Obviously, the doping of SnO with 1% dye extracts modified the XRD patterns of the un-doped SnO samples. Substrate temperature also affected the structural properties of SnO:dye sample depicting increase in intensity vis-à-vis crystallinity of the films with increase in substrate temperature. The results equally indicate that there was an increase in the grain sizes that resulted in a decrease in energy badgap of the samples.