Near-infrared persistent phosphors: Synthesis, design, and applications

Broadband shortwave infrared (SWIR) light-emitting diodes (LEDs), capable of advancing the next-generation solid-state smart invisible lighting technology, have sparked tremendous interest and will launch ground-breaking spectroscopy and instrumental applications. Nevertheless, the device performance is still suppressed by the low quantum efficiency and limited emission bandwidth of the critical phosphor layer. Herein, we report a high-performance Ni2+-doped garnet solid-solution broadband SWIR emitter centered at ∼1450 nm with a large full-width at half-maximum of ∼300 nm, thereby fabricating, for the first time, a directly excited Ni2+-doped garnet solid-solution phosphor-converted broadband SWIR LED device. A synergetic enhancement strategy, adding a fluxing agent and a charge compensator simultaneously, is proposed to deliver a more than 20-fold increase of the SWIR emission intensity and nearly 2-fold improvement of the thermal quenching behavior. The site occupation and mechanism behind the synergetic enhancement strategy are elucidated by a combination of experimental study and theoretical calculation. A prototype of the SWIR LED with a radiation flux of 1.25 mW is fabricated and utilized as an invisible SWIR light source to demonstrate the SWIR spectroscopy applications. This work not only opens a window to explore novel broadband SWIR phosphors but also provides a synergetic strategy to remarkably improve the performance of artificial SWIR LED light sources.

Ni2+-Doped Garnet Solid-Solution Phosphor-Converted Broadband Shortwave Infrared Light-Emitting Diodes toward Spectroscopy Application.

Persistent luminescence and photochromism are two fascinating optical properties that involve charge trapping via defects and their release due to an external stimulation. In both processes, it is possible to define 1 (or on) and 0 (or off) optical states. Consequently, materials with one of these phenomena find major interest in view of designing smart, anticounterfeiting, and optical information storage devices. Combining both processes within a single material can lead to a new generation of information storage phosphors, in which it may be possible to obtain three different optical states by playing on the external stimulations applied on the material. For that purpose, the elaboration of nickel-doped ZnGa2O4 spinet transparent nano-glassceramics is presented in this work. The short-wave infrared (SWIR) emission, a broad band located at ca. 1275 nm, arises from Ni2+ cations located in gallium octahedral sites. SWIR persistent luminescence, arising from the same doping ion transition, can also be monitored after UV charging. Interestingly, UV irradiation not only leads to persistent luminescence charging but also to a reversible photochromism effect. By means of a complete optical characterization study combined with electron paramagnetic resonance measurements, the origins of both the persistent luminescence emission and the photochromism are explored. Finally, a discussion on the advantages of such a material combining both persistent luminescence and photochromism properties, leading to three possible optical states of the material, is dressed in view of possible optical memory systems.

Photochromism and Persistent Luminescence in Ni-Doped ZnGa(2)O(4 )Transparent Glass-Ceramics: Toward Optical Memory Applications

Near-infrared engineering for broad-band wavelength-tunable in biological window of NIR-II and -III: A solid solution phosphor of Sr1-xCaxTiO3:Ni2+

Rechargeable and sunlight-activated Sr3Y2Ge3O12:Bi3+ UV–Visible-NIR persistent luminescence material for night-vision signage and optical information storage

Functional phosphors with shortwave infrared (SWIR) persistent luminescence have attracted an ever-increasing interest from scientists owning to the self-sustainable emission for deeper tissue pene...

Ni2+-Doped Yttrium Aluminum Gallium Garnet Phosphors: Bandgap Engineering for Broad-Band Wavelength-Tunable Shortwave-Infrared Long-Persistent Luminescence and Photochromism

Daoyun Zhu

Papers

Ni2+-Doped Yttrium Aluminum Gallium Garnet Phosphors: Bandgap Engineering for Broad-Band Wavelength-Tunable Shortwave-Infrared Long-Persistent Luminescence and Photochromism