Aluminium-doped zinc oxide deposited by ultrasonic spray pyrolysis for thin film solar cell applications

Aluminum-doped zinc oxide (AZO) thin films were deposited on glass substrates by ultrasonic spray pyrolysis, from metal salt precursors. The electrical and optical properties were investigated as a function of the deposition parameters and the optimum conditions were defined. The thin films exhibit ~80% transparency and a resistivity in the order of 2×10^-2Ωcm. The electrical properties can be improved further with post-deposition annealing in vacuum, or with increase in thickness which causes insignificant transmission losses. AZO nanoparticles can be used as a seed layer and affect the optical properties of the material. The optimized process results in good quality AZO films for their application as the transparent conductive oxide (TCO) layer in thin film solar cells.