Vivid Coloration and Broadband Perfect Absorption Based on Asymmetric Fabry–Pérot Nanocavities Incorporating Platinum

Highly efficient color filtering and broadband perfect absorption are achieved by asymmetric Fabry–Pérot nanocavities incorporating a platinum (Pt) film, which are fabricated on rigid and flexible substrates via a lithography-free deposition process. The absorption band induced by the strong resonance in the asymmetric nanocavity plays a key role in suppressing the corresponding spectral reflection with a high efficiency of over 87% in the nonresonant bands, hence yielding vivid colors. A near-perfect absorption reaching up to 99% is concurrently achieved at the resonance wavelength. The proposed nanocavity configuration features a broad absorption band mediated by an ultra-thin Pt layer and provides a substantially extended color gamut compared to other nanocavities resorting to other noble metals such as silver and gold. Flexible color filters, in conjunction with vivid color printing, are practically demonstrated to provide an outstanding operation largely independent of the angle of incidence and bending/strain in the substrate. A broadband perfect absorber integrated with an antireflection coating is also manufactured to deliver an absorption exceeding 90% in the entire visible band (from λ = 400 to 800 nm). The proposed nanocavity is expected to expedite the development of prominent applications spanning displays, color printing, stealth, and thermal photovoltaics.