Photoluminescence properties of a ScBO3:Cr3+ phosphor and its applications for broadband near-infrared LEDs

摘要

The rapid extension of solid state lighting technologies offers the possibility to develop broadband near-infrared (NIR) phosphor-converted LEDs (pc-LEDs) as novel NIR light sources. In this paper, a new NIR-emitting phosphor ScBO _(3) :Cr ~(3+) was synthesized by a high temperature solid state reaction method. Phase structure, spectroscopic properties, luminescent lifetime, quantum yield, emitter concentration influences and thermal quenching behavior of ScBO _(3) :Cr ~(3+) , as well as its applications for NIR pc-LEDs, were systematically investigated. ScBO _(3) :Cr ~(3+) phosphors exhibit a broad absorption band ranging from 400 to 530 nm, which matches well with the characteristic emission of the blue LED chip. Moreover, Cr ~(3+) ions occupy the Sc ~(3+) sites with relatively low crystal field strength in the ScBO _(3) host, and therefore ScBO _(3) :Cr ~(3+) phosphors show intense broadband emission peaking at ～800 nm upon excitation at 460 nm, originating from spin-allowed ~(4) T _(2) → ~(4) A _(2) transition of Cr ~(3+) ions. The optimum Cr ~(3+) concentration was determined to be ～2 mol% with a quantum yield of ～65%. A broadband NIR pc-LED prototype device was fabricated by the combination of ScBO _(3) :Cr ~(3+) phosphors and a blue LED chip, which showed a maximum NIR light output power of ～26 mW and a corresponding energy conversion efficiency of ～7%. The results indicate the great potential of ScBO _(3) :Cr ~(3+) phosphors for applications in broadband NIR pc-LEDs.