UV- and X-ray-activated broadband NIR garnet-type Ca3Ga2Sn3O12:Fe3+ phosphors with efficient persistent luminescence

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are compact light sources of great interest for NIR spectroscopy applications. Beyond typical Cr 3+ -activated NIR-emitting phosphors, there exists a strong demand for Cr 3+ -free alternatives with high efficiency and broadband emission to rich the landscape of NIR luminescent materials and extend their range of application fields. Here, we report a series of Fe 3+ -activated Ca 3 Ga 2 Sn 3 O 12 garnet-type phosphors exhibiting broadband NIR emission in the 650–1000 nm range attributed to 4 T 1 (G) → 6 A 1 (S) transition, with a maximum at 754 nm and a FWHM of 89 nm upon UV excitation. The spectroscopic results were analyzed according to the Tanabe-Sugano theory from which the crystal field parameter D q and Racah parameters B and C were obtained for the octahedrally coordinated Fe 3+ ion. Notably, the NIR persistent luminescence lasting over 1 h was detected following UV or X-ray irradiation. The possible mechanism involving electron traps was proposed to explain the observed persistent luminescence. Furthermore, a NIR pc-LED was fabricated by coating synthesized phosphor on a UV chip, and its performance was evaluated to assess its potential suitability as a NIR light source. Our discovery of novel type of nontoxic Fe 3+ -activated broadband NIR luminescence phosphors with efficient NIR persistent luminescence paves the way for discovering Cr 3+ -free multifunctional NIR luminescence materials, thereby expanding their application possibilities.