Efficient and ultra-broadband Cr3+/Ni2+ co-doped phosphors for light-emitting diodes with spectral output over NIR-I and NIR-II regions

Abstract

Near-infrared (NIR) phosphor-converted light-emitting diode (pc-LED) technology has attracted intense attention in building next-generation broadband NIR light sources. Simultaneous achievements of ultra-broadband emission and high luminescence efficiency remain a great challenge for the exploration of NIR-emitting phosphors. Herein, an ultrabroad NIR-emitting Cr³⁺/Ni²⁺ codoped MgGa₂(O,F)₄ (MGOF:Cr³⁺,Ni²⁺) phosphor is developed with high quantum efficiency. The site occupation of Ni²⁺, the energy transfer from Cr³⁺ to Ni²⁺, and the influences of Cr³⁺ and Ni²⁺ contents on photoluminescent properties are investigated. The MGOF:Cr³⁺,Ni²⁺ phosphor exhibits an ultrabroad NIR emission from 700 to 1500 nm upon blue light excitation, which arises from the co-luminescence of Cr³⁺ and Ni²⁺. A high internal quantum efficiency of 83.3% and good thermal stability (74.2%@100 °C) are also achieved. The pc-LED fabricated with the MGOF:Cr³⁺,Ni²⁺ phosphor can generate ultrabroad spectral output of NIR light, simultaneously showing a NIR output power of ∼35.5 mW and an energy conversion efficiency of ∼11.9% at 100 mA drive current. Finally, the application of the as-fabricated NIR pc-LED for plastic sorting is also demonstrated. The study provides new clues for the exploration of efficient and ultrabroad NIR luminescence materials.