Double perovskite Cs2AgInCl6:Cr3+: broadband and near-infrared luminescent materials†
Searching for high performance and broader applications of inorganic halide perovskites has drawn extensive attention. In this work, a Cr3+-doped halide perovskite, Cs2AgInCl6:Cr3+, which exhibits broadband near-infrared (NIR) emission is first obtained via the traditional high temperature solid-state reaction. A broad emission band ranging from 850 to 1350 nm centered at 1010 nm with a full-width at half-maximum (FWHM) of 180 nm is assigned to the spin-allowed 4T2 → 4A2 transition of octahedrally coordinated Cr3+ ions in a very weak crystal-field environment. The excitation bands centered at 353, 565 and 800 nm can be attributed to the absorption of the Cs2AgInCl6 host, the Cr3+ d–d transitions of 4A2 → 4T1 and 4A2 → 4T2, respectively. Upon 760 nm excitation, the photoluminescence quantum yield (PLQY) of Cs2AgIn0.9Cl6:0.1Cr3+ is about ∼22.03%. Cs2AgInCl6:Cr3+ phosphors with such broadband NIR emission have potential in phosphor converted light emitting diodes (pc-LEDs) which have applications in bioimaging and biomonitoring.