Highly Thermoduric and Efficient NIR-emitting Garnet Ca3Sc2Ge3O12: Cr3+/Ni2+ via Synergistic A/C-site Regulations with Controllably Afterglow Behaviors for Customized Applications

Simultaneous realizations of high thermal stability and quantum efficiency (QE) in phosphors with near-infrared (NIR) photoluminescence (PL) and long-persistent PL (LPL) attributes are a daunting task. Herein, we have come up with a dual-site co-substitution scheme in Ca 3 Sc 2 Ge 3 O 12 : Cr 3+ /Ni 2+ to concurrently actualize high-quality NIR-I/II (L)PL via either equivalent or aliovalent co-substitution at indirect lattice A/C sites of [Y 3+ + Al 3+ ] or [Y 3+ + Si 4+ ] for [Ca 2+ + Ge 4+ ]. Both Cr 3+ and Ni 2+ are colonized at B site (Sc 3+ ) under weak crystal field environment and emitting continuous PL across NIR-I/II regions via energy transfer from Cr 3+ to Ni 2+ under blue-light excitation. Due to inequivalent replacement of Ni 2+ at Sc 3+ site and consequential production of defects, a charming NIR LPL is also gained. Further incorporation of [Y 3+ + Al 3+ ] unit begets densified robust framework with [Sc(Cr/Ni)O 6 ] octahedral distortion, elucidating the mechanism of improved properties in PL QE (76.23%) and stability (89.5%@423 K). While [Y 3+ + Si 4+ ] modulation in Ca 3 Sc 2 Ge 3 O 12 not only brings rigid structure but also suppresses defects (LPL) because of equivalent triple-unit between Y 3+ /Si 4+ /Ni 2+ and Ca 2+ /Ge 4+ /Sc 3+ . A NIR pc-LED based on the designed phosphor with a commercial 460 nm blue LED chip is fabricated and reveals multi-applications in nondestructive detection, bioimaging, and anticounterfeiting. This work provides new perspectives for developing high-performance NIR-emitting phosphor materials. This study reveals the state-of-the-art researches on both NIR-I/II-emitting (L)PL phosphors with high QE and thermal stability from Cr/Ni-activated in garnet Ca 3 Sc 2 Ge 3 O 12 and their multiple applications in the NIR pc-LED, non-destructive detection, and anticounterfeiting. The proposed A/C-site regulation and ET from Cr to Ni pave a new way to design NIR-I/II phosphor and expands their related optoelectronic applications. Download: Download high-res image (298KB) Download: Download full-size image