Achieving Nearly Quantitative (∼100%) IQE and 42.3% EQE Across NIR‐I and NIR‐II Regions with Cr<sup>3+</sup>‐doped Cs<sub>2</sub>NaScCl<sub>6</sub> under 300 nm Excitation
Chunli Zhao, Yuan Gao, Jing Wang, Jianbei Qiu
Abstract
Abstract Lead‐free rare‐earth‐based perovskites have received widespread attention for their unique optical properties, although achieving efficient broadband near‐infrared (NIR) emission with these materials remains a challenge. Here the synthesis of a rare earth‐based double perovskite (Cs 2 NaScCl 6 ) by an improved solid phase method is reported. The doping of Cr 3+ led to the formation of [CrCl 6 ] 3− octahedron, which exhibited a broadband NIR emission peaked at 950 nm and a half‐peak width of 162 nm. It is worth noting that with the same actual Cr 3+ content, the luminous intensity of Cs 2 NaScCl 6 synthesized by the improved solid‐phase synthesis is four times higher than the product synthesized by the hydrothermal method. an efficient Cl − ‐Cr 3+ charge transfer sensitization facilitated by localized electrons in [CrCl 6 ] 3− octahedron is the mechanism for the strong NIR emission of Cr 3+ is proposed. Calculations based on density functional theory and Bader charge analysis support the notion that electrons in [CrCl 6 ] 3− octahedrons are strongly localized in Cs 2 NaScCl 6 :Cr 3+ , which is conducive to the Cl − –Cr 3+ charge transfer process, resulting the internal quantum efficiency of 100% and external quantum yield as 42.3%. The highly efficient ultra‐broadband NIR emission with excellent stability offers many opportunities for applications in the field of NIR night vision and bio‐imaging.