High-efficiency and thermally stable Cr3+-doped BaSiF6 fluoride phosphors for broadband near-infrared LED applications

Abstract

Broadband near-infrared (NIR) light sources have emerged as crucial components in a wide array of technological applications, spanning from advanced imaging systems to night vision devices and healthcare therapy. The advent of light-emitting diodes (LEDs) has unlocked new opportunities for broadband NIR phosphor-converted LEDs (NIR pc-LEDs), characterized by improved efficiency, compact form factors, and low operating temperatures. However, high-performance NIR phosphors for high-power LEDs remain scarce. In this work, Cr³⁺-doped fluorides BaSiF₆:xCr³⁺ (where x ranges from 2.5 % to 15 %) have been designed and synthesized, which offer high quantum efficiency and thermal stability to maintain ∼80 % intensity at 450 K. Theoretical simulations demonstrate that BaSiF₆, with a sufficiently large electronic bandgap of 7.8 eV, possesses the full potential to host NIR luminescent activators. Furthermore, molecular dynamics (MD) simulations validate its good thermal stability, enduring high temperatures exceeding 600 K annealing. The fabricated NIR pc-LED device using BaSiF₆:Cr³⁺ demonstrates high light output power and photoelectric efficiency under multiple driven currents, making it suitable for a wide range of applications as NIR light source. Capitalizing on the above merits, a prototype NIR transmission detector is demonstrated for potential applications in non-invasive material inspection and security systems. This research expands the repertoire of high-performance NIR phosphors for multifunctional use.