Ultrathin Bimetal Color Filter Based on Plasmonic Nanostructure

Plasmonic subtractive color filters through a nanostructured ultrathin Ag film have attracted intensive attention due to their good durability, high color tunability and high transmission. However, Ag film suffers from discontinuity when the thickness is below 15 nm, which limits the further increasement of transmission efficiency. Herein a bimetal ultrathin (~10 nm) subtractive color filter with one dimensional nanogratings was demonstrated and fabricated. By adding an embedded Al layer to suppress the formation of Ag islands, a smooth, continuous and reliable bimetal film was obtained. At the same time, the blue shift of transmission minimum was beneficial to overcome difficulty in nanostructure fabrication. This method also provided a new approach to tune the color by simply varying the thickness of Al layer. A broad palette of colors, including cyan, magenta and yellow, was attained in bimetal color filter with high transmission beyond 80%.