Trivalent Chromium Ions Doped Fluorides with Both Broad Emission Bandwidth and Excellent Luminescence Thermal Stability.

Recently, trivalent chromium ion doped phosphors have exhibited significant application potential in broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs). However, developing an NIR phosphor with both broad emission bandwidth and excellent luminescence thermal stability is still a great challenge. Here, we demonstrate an NIR phosphor, ScF:Cr, which can fulfill both conditions simultaneously. The prepared phosphors show broadband emission in the range of 700 to 1100 nm, with a full width at half-maximum (FWHM) of 140 nm peaking at 853 nm. These phosphors also demonstrate an excellent luminescence thermal stability (the emission intensity of ScF:Cr keeps 85.5% at 150 °C compared with the value at room temperature). An NIR pc-LED based on blue LED chips was fabricated and tested. The results show that the NIR pc-LED can yield strong broadband NIR emission. This work not only provides a promising phosphor for the application of NIR pc-LEDs but also has important guiding significance for effect of synthesis conditions on the luminescence properties of Cr-doped fluorides.