Cr<sup>3+</sup>/Yb<sup>3+</sup> Codoped Cs<sub>2</sub>NaInCl<sub>6</sub> Double Perovskites for Near-Infrared Light-Emitting Diodes
Xinyu Fu, Huwei Li, Hongxia Yue, Zheyu Li, Jing Feng, Hongjie Zhang
Abstract
Near-infrared (NIR) light-emitting diodes (LEDs) are potential devices that could become the core components in biological imaging, security monitoring, etc., which are currently constrained by suboptimal luminous efficiency due to the absence of excellent luminescent materials. Here, we report a double perovskite Cs 2 NaInCl 6 that is suitable for Cr 3+ doping and exhibits broad NIR emission. Through direct absorption and energy transfer (ET) from the self-trapped excitons (STEs) induced in the Cs 2 NaInCl 6 matrix, Cr 3+ can be excited to 4 T 1 (P), 4 T 1 (F), and 4 T 2 (F) levels. Then, the broad emission with a full width at half-maximum ( FWHM ) of ∼150 nm, spanning 800 to 1300 nm, and a high photoluminescence quantum yield (PLQY) of up to 70% can be realized, resulting from the 4 T 2 → 4 A 2 transition of Cr 3+ . Subsequently, the introduction of Yb 3+ endows Cs 2 NaInCl 6:Cr 3+,Yb 3+ with a higher PLQY of 76% at the optimal doping ratio than Cs 2 NaInCl 6:Cr 3+ . Ultimately, a miniaturized NIR LED device packaged based on Cs 2 NaInCl 6:15%Cr 3+,15%Yb 3+ has been fabricated, which demonstrates superior performance for night vision, traceless perspective detection, and biological imaging. This work not only screens out a suitable Cs 2 NaInCl 6 matrix for Cr 3+ doping with high PLQY but also promotes its luminescence performance through Yb 3+ doping for NIR LED applications.