Vivid reflective color generation mechanism in Al/AAO/Al configuration

Abstract

Lithography-free metal-dielectric-metal (M/D/M) configuration has attracted tremendous interest for vivid reflective color generation, especially the M/anodic aluminum oxide (AAO)/Al configuration due to its simple, cost-effective and flexible preparation processes. However, the physical mechanism of structural color generation in M/AAO/Al configuration has not been sufficiently discussed. Here, the Al/AAO/Al configurations with distinct vivid reflective colors were prepared. To reveal the color generation mechanism, the bumpy nanopore Al island film (BAlIpore) was proposed as the top meal layer. The optical properties of BAlIpore and BAlIpore/AAO/Al configurations are investigated by both experimental and finite-difference time-domain (FDTD) method. The results indicate that BAlIpore/AAO/Al configuration can generate vivid reflective colors due to the large enhancement and widening of the absorptive band in the reflective spectrum, which is the result of the strong coupling between the broadband local surface plasmon resonance (LSPR) and destructive interference (thin-film interference) supported by BAlIpore and BAlIpore/AAO/Al, respectively. Furthermore, the optical properties of the Al/AAO/Al configuration with a planar nanopore Al film (PAlpore) as the top metal layer are investigated by FDTD method and the results indicate that the PAlpore/AAO/Al configuration can’t result in vivid reflective colors because of the limit enhancement and widening of the absorptive band in the reflective spectrum, which resulted in the weak coupling between weak broadband non-resonance scattering and F-P resonance supported by the PAlpore and PAlpore/AAO/Al, respectively. The results contribute to our understanding of the vivid reflective color generation mechanism in the M/AAO/Al configuration and can be used to develop a reflective filter, color display, etc.