Octave-spanning broad luminescence of Cr³⁺, Cr⁴⁺-codoped Mg₂SiO₄ phosphor for ultra-wideband near-infrared LEDs

Abstract

We synthesized Cr3+, Cr4+-codoped Mg2SiO4 phosphors and studied their optical properties for application as a novel wideband near-infrared (NIR) light-source. The phosphors have an ultra-wideband NIR luminescence spectrum of 650–1400 nm. The origin should be the transition of Cr3+ and the transition of Cr4+. The luminescence spectrum spans over one octave range and covers the “optical window in biological tissues”. We successfully achieved an ultra-wideband luminescence of 650–1400 nm with a maximum output power of 367.5 μW by combining a blue LED with Cr3+ and Cr4+-codoped Mg2SiO4 phosphors in a single package.

Broadband Short-Wave Infrared Light-Emitting Diodes Based on Cr3+-Doped LiScGeO4 Phosphor

“…Tetravalent chromium (Cr 4+ ) is also a promising luminescent center for SWIR photoluminescence because of its broadband and tunable emissions in a wavelength range over 1100–1700 nm as a result of the characteristic 3 T 2 → 3 A 2 electronic transition . The broadband SWIR emission form Cr 4+ is mainly found in laser crystals and glasses, including Y 3 Al 5 O 12 :Cr 4+ crystal and Cr 4+ doped glass ceramics (Zn 2 SiO 4 , Mg 2 SiO 4 , Li 2 ZnSiO 4 , Li 2 MgSiO 4 , and Ca 2 GeO 4 :Cr 4+ ). , Recently, a handful of Cr 4+ -doped ceramic phosphors have been reported by introducing Cr 4+ into tetrahedral sites intentionally or unintentionally. ,− However, SWIR light emission beyond 1000 nm from Cr 4+ usually coexists with the dominant Cr 3+ NIR light emission. By far, although there are increasing interests for advanced applications ranging from night vision imaging to SWIR detection application, the research progress on the development and application of chromium (Cr 3+ /Cr 4+ )-doped phosphors in the SWIR is rather slow…”

Molten Salt Synthesis of Broad-Band Near-Infrared InBO3:Cr3+ Submicron Phosphor and Its Luminescent Enhancement by Lanthanide Ion Codoping

“…NIR light sources have widespread applications in a variety of fields including optical communication, spectroscopy, bioimaging, food analysis, and night vision illumination. − Traditional NIR light sources, such as incandescent bulbs and halogen lamps, can provide continuous NIR light output but have disadvantages of large size, short lifetime, and low efficiency. , NIR light-emitting diodes (LEDs) have a small size, long lifetime, and high energy conversion efficiency. However, the narrow bandwidth limits their applications in spectroscopic analysis (e.g., analysis of the contents of water, sugar, or pesticides in foodstuffs). , Benefiting from the rapid technological developments of white pc-LEDs, the combination of efficient blue LED chips and NIR-emitting phosphors is an ideal strategy to build next-generation broad-band NIR light sources. NIR pc-LEDs can overcome the inherent limitations of current NIR light sources, simultaneously showing relatively high efficiency, tunable broad-band emission, compact size, low cost, and excellent durability. , Accordingly, appropriate broad-band NIR-emitting phosphor materials are the key components of NIR pc-LED devices.…”

“…However, the narrow bandwidth limits their applications in spectroscopic analysis (e.g., analysis of the contents of water, sugar, or pesticides in foodstuffs). 7,8 Benefiting from the rapid technological developments of white pc-LEDs, the combination of efficient blue LED chips and NIR-emitting phosphors is an ideal strategy to build next-generation broad-band NIR light sources. NIR pc-LEDs can overcome the inherent limitations of current NIR light sources, simultaneously showing relatively high efficiency, tunable broad-band emission, compact size, low cost, and excellent durability.…”

Crystallographic control for Cr4+ activators toward efficient NIR-II luminescence

“…Unlike rareearth doped NIR-II phosphors, Cr 4+ -doped phosphors such as Mg 2 SiO 4 :Cr 4+ , Ca 2 Al 2 SiO 7 :Cr 4+ and Mg 14 Ge 5 O 24 :Cr 4+ show broadband emission ranging from 1000 to 1400 nm with a peak wavelength of over 1200 nm. [28][29][30] However in inorganic compounds, the chromium ions show a strong tendency to locate at octahedral sites and form a trivalent state. 31 Thus, the Cr 4+ NIR-II luminescence may be deteriorated with the existence of octahedral sites in a host lattice.…”