| Abstract |
| With the expanding development of flexible optoelectronic devices, the need for high-performance (i.e., high conductivity, high transmittance and flexibility) transparent conductive electrodes has grown. In this study, the critical role of thickness for each of the layers in ZnO/Cu/ZnO transparent conductive electrodes (TCE) for optoelectronic devices has been investigated. The Ag layer deposited on the bottom ZnO exhibited sheet resistance lower than 10 Ω/Sq. at a Ag thickness of 8 nm. It was then fixed with a top and bottom ZnO layer, whose thicknesses were independently varied to achieve the optimized transmittance of visible light. The variation in thickness of the top and bottom ZnO layers, which serve as anti-reflection layers as well as anti-oxidation layers, resulted in a significant modulation of the transmittance behavior. In particular, the relatively low transmittance in the wavelength range of 400-500 nm was shown to be strongly affected, requiring further thickness optimization. The optimized thicknesses for the top and bottom ZnO layers were found to be 30 and 40 nm, respectively, with the corresponding average visible light transmittance of 85% and peak transmittance of 95%. According to the Haccke figure of merit, the value for the optimized ZnO/ Ag/ZnO electrode was 0.021, which surpasses the reported values of Cu-based electrodes.
(Received September 18, 2019; Accepted October 28, 2019) |
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| Key Words |
| copper, zinc oxide, transparent conductive electrodes, thin films |
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