Subwavelength Plasmonic System for Producing Vivid Color

Abstract

Researchers at the University of Central Florida have developed a plasmonic display device that solves the issues that have hampered other plasmonic color technologies: severe angle sensitivity, specular reflection and limited fabrication techniques. The UCF subwavelength plasmonic system overcomes these challenges while producing a vivid subtractive color space (cyan, yellow, magenta and black, also known as CMYK).

Color generated through organic pigments contains chemicals that can degrade over time due to environmental exposure and light bleaching. In contrast, color due to structural resonances in metallic nanostructures does not bleach in sunlight and can be designed through their underlying dimensions. In this way, a whole spectrum of colors can be achieved through nanostructures made from only one metal and its complimentary oxide.

The UCF invention employs a highly reproducible self-assembling technique where aluminum particles are formed through a temperature- and pressure-dependent thin-film growth mechanism in an ultra-high vacuum electron beam evaporator. The process is compatible with and takes on the scattering properties of underlying arbitrary substrates and can result in completely diffusive, angle-independent and flexible plasmonic color surfaces.

Technical Details

The UCF plasmonic system comprises a dense array of aluminum nanoparticles formed on top of an oxide-coated aluminum backplane. Ambient white light excites resonances within the structure, which are confined to the gaps between particles. The resonances demonstrate a high degree of angle independence, and their spectral location is a function of the size distribution of the aluminum particles, the surrounding refractive index, and the optical distance from each other and the mirror. Light, which is not absorbed by the surface, is reflected to result in a perceived color.

In one example configuration of the invention, a display device includes a substrate, a plasmonic aluminum reflector layer over the substrate, and a conducting oxide layer over the plasmonic aluminum reflector layer. The device has a circular polarizer over the conducting oxide layer and is configured to receive incident visible radiation, which causes plasmon resonance within the plasmonic aluminum reflector layer. Also included in the device is a circuit configured to apply a voltage between the conducting oxide layer and the plasmonic aluminum reflector layer. The placement causes the plasmonic aluminum reflector layer to selectively reflect the incident visible radiation based on the voltage. The narrow, sub-10 nm gaps between particles and the mirror hybridize individual plasmonic modes and manifest a single angle-insensitive resonance with nearly 100 percent absorption of light at a desired wavelength.

Partnering Opportunity

The research team is seeking partners for licensing and/or research collaboration.

Stage of Development

Prototype available.

Benefit

Market Application

Publications

Self-assembled plasmonics for angle-independent structural color displays with actively addressed black states, Proceedings of the National Academy of Sciences of the United States of America, June 3, 2020 | 117 (24) 13350-13358 | https://doi.org/10.1073/pnas.2001435117.