Cr3+/Yb3+ Codoped Cs2NaInCl6 Double Perovskites for Near-Infrared Light-Emitting Diodes

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 Cs2NaInCl6 that is suitable for Cr3+ doping and exhibits broad NIR emission. Through direct absorption and energy transfer (ET) from the self-trapped excitons (STEs) induced in the Cs2NaInCl6 matrix, Cr3+ can be excited to 4T1(P), 4T1(F), and 4T2(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 4T2→4A2 transition of Cr3+. Subsequently, the introduction of Yb3+ endows Cs2NaInCl6:Cr3+,Yb3+ with a higher PLQY of 76% at the optimal doping ratio than Cs2NaInCl6:Cr3+. Ultimately, a miniaturized NIR LED device packaged based on Cs2NaInCl6:15%Cr3+,15%Yb3+ has been fabricated, which demonstrates superior performance for night vision, traceless perspective detection, and biological imaging. This work not only screens out a suitable Cs2NaInCl6 matrix for Cr3+ doping with high PLQY but also promotes its luminescence performance through Yb3+ doping for NIR LED applications.