Triple-Responsive Visible-To-Ultraviolet-C Upconverted Photons for Multifunctional Applications

Optically upconverted materials that are capable of converting long-wavelength low-energy photons into short-wavelength high-energy light have found their applications over a broad spectrum of fields, like light-emitting diodes (LEDs), displays, bio-detection, etc. Despite the great advances in exploring the conventional near-infrared-to-visible or even near-infrared-to- ultraviolet upconverted materials, the visible-to-ultraviolet-C counterparts are far from being desired. Here, a new triple-responsive material is introduced, i.e., Pr3+-doped Li2SrGeO4. It has the ability to absorb the visible photons at approximate to 450 nm from LEDs, laser diodes (LDs), and even sunlight and emit the ultraviolet-C (UVC) light covering the 240-280 nm wavelength range. Considering the unique characteristics of the UVC photon, the promising applications of the material are further demonstrated in several scenarios, including static/dynamic labeling under the excitation of a 450 nm LED, information encryption under excitation of sunlight, and sterilization under excitation of a 450 nm LD. The work enriches the library of optically upconverted visible-to-UVC materials and widens the application scenarios of these materials.