Silver nanoparticle decorated ZnO nanorod arrays on AZO films for light absorption enhancement



The silver (Ag) nanoparticle (NP) decorated zinc oxide (ZnO) nanorod arrays (NRAs) on aluminum-doped ZnO (AZO) coated glass substrates were fabricated by the wet chemical synthesis of ZnO and a subsequent thermal evaporation of Ag without thermal annealing. The optical properties of ZnO NRAs with different sized Ag NPs were investigated for light absorption enhancement, in comparison with the Ag on glass substrate. The nominal size and the amount of Ag NPs were controlled by changing the evaporation time. As the evaporation time was increased from 200 to 1000 s, the amount of Ag NPs of ≲ 50 nm attached to ZnO NRAs was increased, leading to a significant increase of light absorption due to the enhanced localized surface plasmon resonance (LSPR) compared to the Ag on glass substrate. However, at a long evaporation time of 2000 s, the evaporated Ag did not exhibit the peak of LSPR because the deposited Ag NPs become excessively agglomerated. At evaporation times of 200–1000 s, the resonance peaks of the ZnO NRAs with Ag NPs were observed at λ ∼ 463–508 nm. After evaporating at 1000 s, the peak absorptance of 94% was achieved.