Effect of seed particle size and ammonia concentration on the growth of ZnO nanowire arrays and their photoconversion efficiency

ZnO nanowire arrays were synthesised for dye-sensitised solar cell applications using the chemical bath deposition technique. To study the effect of the particle size in the seed layer on the growth and resultant photoconversion efficiency, we prepared various seeded FTO substrates by repeating the seed layer sol-gel coating process. It was found that changing the number of coating process merely increases the particle size of the ZnO seeds, and the increase in the seed particle size induces low growth rates. In addition, to enhance the nanowire growth rates, ammonia was added with polyethylenimine. Based on various characterisations such as XRD, SEM, and J-V curves, we discuss the effect of ammonia on the growth rates of ZnO nanowire, and suggest the optimum ammonia concentration for solar cell applications.