I dissolved hydrated nickel chloride in de-ionized water, stirred for 30 minutes to prepare 0.2 M solution. Uniform film was grown on a pre-heated glass substrate but film absorbed moisture and liquified.
chloride based compound is not good for thin film especially for spray pyrolysis technique. so you may used acetate or nitrate based nickel compound. you can change the molar concentration as well as deposition temperature.