Broadband
light absorbers are attractive for their applications
in photodetection and photothermic conversion. Metal black absorbers
are highly nanoscale porous deposits in the presence of inert gas
and exhibit nanoscale structure. Silver nanoparticles have attracted
intensive research interest because of their distinctive electrical
and optical properties. Here, we fabricated a number of silver black
films with nanoscale thicknesses under various gas ambient atmospheres
(He and Ar). Our aim is to fabricate broadband absorbers with high
absorption performance from the visible-to-mid-IR (MIR) spectral range
and investigate their aging behaviors. The He-ambient silver black
film exhibited average absorption coefficients of 3.17, 2.27, and
1.81 μm–1 in the visible, near-IR (NIR), and
MIR ranges, respectively, with the highest value of 6.50 μm–1 at a wavelength of 357 nm. Those of the Ar-ambient
film were 0.48, 0.51, and 0.443 μm–1 in visible,
NIR, and MIR ranges, respectively. The absorption coefficients of
the He-ambient film were much higher than those of the Ar-ambient
film, which were very promising candidates as broadband absorbers.
Moreover, metal black films suffered from aging phenomena because
of their nanoscale porous structure. The long-term stability of the
optical properties was worthy of attention for applications. Therefore,
the room temperature aging behaviors of nanoscale-thick silver black
films were investigated. Comparative analyses of the atomic content
before/after aging demonstrated that the aging was attributed to crystallization,
deliquescence, and oxidation. Comparative analyses of the absorption
and photothermal response characteristics before/after aging were
also performed. The results demonstrated that the nanoscale-thick
silver black films possessed great absorption stability in the visible-to-MIR
range and photothermal response stability, which can provide valuable
reference for applications of broadband absorbers such as IR dynamic
scene generation.