Cr3+-doped LiAl5O8 Nanocrystals Embedded in Transparent Glass-ceramic with High NIR PLQY and Excellent Thermal Stability

The performance and service life of a traditional NIR phosphor-converted light-emitting diodes sealed by epoxy resin are affected over time due to the low thermal conductivity of the casting material that leads to excessive heat build-up, an accelerated aging and discoloration of the resin. Here, we report the synthesis and characterization of a highly efficient NIR emitting LiAl 5 O 8 :Cr 3+ nanocrystals embedded in transparent glass-ceramic. Under 415 nm light excitation the emission, the new NIR phosphor exhibits NIR emission in sharp lines covering 650∼1000 nm to originate from the spin-allowed 4 T 2 / 2 E→ 4 A 2 transition of Cr 3+ ions, with an emission peak at ∼ 720 nm and an optimal PLQY of about ∼ 41.28%. The NIR emission originates from the spin-allowed 4 T 2 / 2 E→ 4 A 2 transition of Cr 3+ . The transparent glass-ceramic showed excellent luminescence thermal stability; the integrated luminescence intensity measured at 383 K is ∼ 66.55% of that measured at room temperature (303 K). We constructed a NIR pc-LED light source device by coupling a piece of LiAl 5 O 8 :Cr 3+ nanocrystal-laden glass-ceramic and a purple LED chip and performed characterization of the luminescence properties of this device. The potential application of this device in NIR imaging was demonstrated. Our study provides a basis for further development of thermal stable and highly efficient transparent glass-ceramic based NIR luminescence materials and the exploration for their applications.