An ultra-flexible plasmonic metamaterial film for efficient omnidirectional and broadband optical absorption.

An omnidirectional and broadband optical absorber has long been pursued for its wide application in optics, sensing and energy fields. The recent development of flexible and non-planar optoelectronic devices, however, poses a great challenge to fabricate an optical absorber with excellent mechanical flexibility. Here, based on a facile solution method, we demonstrate an ultra-flexible plasmonic metamaterial film (PMF), which is a composite of gold nanoparticles (Au NPs) and aramid nanofibers, to achieve omnidirectional and broadband optical absorption. Due to the comprehensive contributions of the anti-reflection effect of the PMF surface, localized surface plasmon resonances of the Au NPs, and non-resonant decay of light inside the nanocomposite, the PMF exhibits highly efficient omnidirectional and broadband absorption at visible and near-infrared frequencies. In addition, it also presents exceptional mechanical and fast collective light-heating properties, which makes it promising to be applied on flexible and non-planar photo-thermal devices.