Visualization of UV by Nanopatterned Down-Shifting Materials Mimicking Human Retinal Cone Cells

Abstract

The conversion of invisible ultraviolet (UV) light to visible light by down-shifting (DS) materials has a variety of important applications in the fields of optoelectronics and photonics. The ability to control emission colors as a function of the wavelength of incident UV light would significantly advance scientific research and technological applications. A novel strategy for UV visualization is demonstrated that employs nanoimprint lithography combined with a sol-gel process. The principles of trichromacy of human vision are applied; three DS materials sensitive to three different ranges of UV light are nanopatterned to mimic the three types of cone cells in the human retina. Each DS material then emits a distinctive color that can be recognized by each type of cone cells for visualization. The nanopatterned structure significantly intensifies the light emission by Mie scattering and spatially separates the three DS materials, thereby minimizing unwanted optical interference among them. The deliberately designed triple-nanopatterned DS materials exhibit various emission colors ranging from green, to orange, to pink depending on the wavelength of the incident UV light. The current work would contribute to the development of novel strategies for multicolor tunable emission that may lead to innovative applications.