We engineered an epsilon-near-zero (ENZ) material from suitably disordered metallic nanostructures. We create a new class of dispersionless composite materials that efficiently harnesses white light. By means of Atomic Force Microscopy (AFM) and Photoluminescence (PLE) measurements we experimentally demonstrate that this nanomaterial increases up to a record value the absorption of ultra-thin light harvesting films at visible and infrared wavelengths. Moreover, we obtained a 170% broadband increase of the external quantum efficiency (EQE) when these ENZ materials are inserted in an energy-harvesting module. We developed an inexpensive electrochemical deposition process that enables large-scale production of this material for energy-harvesting applications.
Structural colours represents a research area of great interest, due to a wide field of application ranging from micro-security to biomimetic materials. At present metallic substrate are heavily employed and only a partial spectra of colours can be realised. We propose a novel, metal-free technology that exploits the complex scattering from a disordered three-dimensional dielectric material on a silicon substrate. We reproduce experimentally the full spectrum of CMYK colours, including variations in intensity. Our resolution lies in the nm range, limited only by the electron beam lithography fabrication process. We demonstrate that this technique is extremely robust, suitable for flexible and reusable substrates. Full of these notable proprieties these nano-structures fits perfectly with the requirements of a real-world technology.