Performance of Transparent Metallic Thin Films

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The ability to maintain high electrical conductivity and optical transparency simultaneously under mechanical deformation has made transparent metallic films (TMFs) the best candidates among transparent conductive films (TCFs). However, there is a lack of suitable models to predict the overall performance of the TMFs. Here, empirical relationships for resistance R_s based on the network resistor model, Kirchoff’s rules, and the thickness-dependent resistivity and transmission T based on the effective medium theory, the geometric model, and the Beer–Lambert law are proposed. A systematic thickness t- and perforation area ratio PR-dependent study on the silver nanohole array TMF has been performed. Both models fit well with our experimental data as well as the data reported in the literature, regardless of the lattice structure of the TMFs. A general and comprehensive figure-of-merit (FOM) expression for TMFs, Φ = T^β/R_s, is obtained. Both the experimental data and the theoretical predictions show that β = 5 is better to characterize the performance of nanohole array TMFs as compared to β = 10 for TCFs. The observed empirical models and the FOM expression not only can be used to assess the overall quality of any type of TMFs but also provide guidance for fabrication.