The ultra-wideband near-infrared luminescence properties and applications of K2SrGe8O18:Cr3+ phosphor
Yixin Sun, Mengmeng Shang, Yining Wang, Yiying Zhu, Xiaole Xing, Peipei Dang, Jun Lin
Abstract
The near-infrared (NIR) light sources are fascinating in real-time nondestructive examination applications. Given that chemical bonds in organic substances (such as C–H, O–H and N–H) have extensive absorption and reflection of light in the NIR region , the emission spectrum of the NIR light sources should be as broad as possible. In this work, ultra-wideband K 2 SrGe 8 O 18 (KSGO):Cr 3+ NIR-emitting phosphors with a 650–1200 nm emission span are developed. Structural analysis combined with electron paramagnetic resonance (EPR), photoluminescence (PL) spectra, time-resolved spectrum (TRES) and temperature-dependent PL spectra confirm that the super broadband emission with full width at half-maximum (FWHM) of 214 nm originates from the double Cr 3+ luminescence centers occupying different [GeO 6 ] octahedra . Li + ion as charge compensator is introduced to balance the negative charge induced by the un-equivalent replacement of Cr 3+ for Ge 4+ , and the PL intensity and thermal stability are greatly enhanced. The NIR phosphor-converted luminescent diodes (pc-LEDs) prepared by combining optimized KSGO:0.10Cr 3+ , 0.07Li + samples with 460 nm LED chips demonstrate their application in night vision. The measured absorption spectra of hemoglobin, water, ethyl alcohol and peanut oil illuminated by the as-prepared KSGO:0.10Cr 3+ , 0.07Li + phosphors indicate nondestructive analysis in the areas of food safety.