Double perovskite Cs ₂AgInCl ₆:Cr ³⁺: broadband and near-infrared luminescent materials

Abstract

A Cr ³⁺-doped halide double perovskite Cs ₂AgInCl ₆:Cr ³⁺ is first reported which exhibits a broad near-infrared emission ranging from 850 to 1350 nm centered at 1010 nm with a FWHM of 180 nm.

Abstract

Searching for high performance and broader applications of inorganic halide perovskites has drawn extensive attention. In this work, a Cr ³⁺-doped halide perovskite, Cs ₂AgInCl ₆:Cr ³⁺, 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 ⁴T ₂ → ⁴A ₂ transition of octahedrally coordinated Cr ³⁺ 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 Cs ₂AgInCl ₆ host, the Cr ³⁺ d–d transitions of ⁴A ₂ → ⁴T ₁ and ⁴A ₂ → ⁴T ₂, respectively. Upon 760 nm excitation, the photoluminescence quantum yield (PLQY) of Cs ₂AgIn _0.9Cl ₆:0.1Cr ³⁺ is about ∼22.03%. Cs ₂AgInCl ₆:Cr ³⁺ phosphors with such broadband NIR emission have potential in phosphor converted light emitting diodes (pc-LEDs) which have applications in bioimaging and biomonitoring.