American Chemical Society
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Broadband Omnidirectional Light Trapping in Gold-Decorated ZnO Nanopillar Arrays

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journal contribution
posted on 2017-03-16, 00:00 authored by Yuan-Ming Chang, Man-Ling Lin, Tung-Yen Lai, Chang-Hung Chen, Hsin-Yi Lee, Chih-Ming Lin, Yew-Chung Sermon Wu, Yen-Fu Lin, Jenh-Yih Juang
The photoluminescence (PL) and reflectivity characteristics of zinc oxide nanopillars (ZnO-NPs) grown on indium–tin–oxide (ITO)-coated glasses were investigated. The room temperature PL showed bright white-light emission for the undoped ZnO-NPs grown at 600 °C, suggesting the close relation between the optical characteristic and the growth conditions being carried out for obtaining the present ZnO-NPs. The reflectivity of the as-grown ZnO-NPs array was about ∼29% with the wavelength of the incident light ranging from 200 to 1800 nm. Nevertheless, the reflectance reduced significantly to less than 9.9% when a layer of gold (Au) was deposited on ZnO-NPs by sputtering for 5 min, corresponding to more than 65% reduction in Au-coated ZnO-NPs (Au/ZnO-NPs). Moreover, the angle-resolved reflectance measurements on the present Au/ZnO-NPs array show an omnidirectional light-trapping characteristic. These remarkable characteristics, broadband and omnidirectional light-trapping of Au/ZnO-NPs, are attributed to the extended effective optical path of the incident light due to subwavelength scattering resulting from the presence of Au nanoparticles.