ZnO thin films deposition by spray pyrolysis: Influence of precursor solution properties

Zinc oxide (ZnO) thin films were deposited by spray pyrolysis technique using different precursors. Three starting solutions salts namely: zinc acetate, zinc chloride and zinc nitrate were used. The properties of these solutions and their influence upon ZnO films growth rate are investigated. The obtained results indicate that the dissociation energy of the starting solution plays an important role on films growth rate. A linear relationship between the solution dissociation energy and the growth rate activation energy was found. However, the surface tension of the used solution controls the droplet shape impact. Both solution surface tension and dissociation enthalpy alter the microstructure of the formed film. Films deposited with zinc acetate are characterized by a smooth surface, dense network and high transparency, while films deposited with zinc chloride have a better crystallinity and low optical transmittance. ► The solution surface tension and dissociation enthalpy of the precursor alter the droplet dynamic. ► A linear relationship between the solution dissociation energy and the growth rate activation energy was found. ► Both precursor surface tension and dissociation enthalpy control film microstructure. ► SEM image reveals that film deposited with zinc chloride is composed with separated hexagonal ZnO columns. ► Films deposited with acetate and nitride precursors have a dense microstructure.