Wide-coverage and Efficient NIR Emission from Single-component Nanophosphors through Shaping Multiple Metal-halide Packages.

Wide-coverage near infrared (NIR) phosphor-converted LEDs possess promising potential for practical applications, but little is developed towards the efficient and wide-coverage NIR phosphors. Here, we report the single-component lanthanide (Ln 3+ ) ions doped Cs 2 M(In 0.95 Sb 0.05 )Cl 6 (M=alkali metal) nanocrystals (NCs), exhibiting emission from 850 to 1650 nm with high photoluminescence quantum yield of 20.3 %, which is accomplished by shaping the multiple metal halide octahedra of double perovskite via the simple alkali metal substitution. From Judd-Ofelt theoretical calculation and spectroscopic investigations, the shaping of metal halide octahedra in Cs 2 M(In 1-x Sb x )Cl 6 NCs can break the forbidden of f-f transition of Ln 3+ , thus increasing their radiative transition rates and simultaneously boosting the energy transfer efficiency from host to Ln 3+ . Finally, the wide-coverage NIR LEDs based on Sm 3+ , Nd 3+ , Er 3+ -tridoped Cs 2 K 0.5 Rb 0.5 (In 0.95 Sb 0.05 )Cl 6 NCs are fabricated and employed in the multiplex gas sensing and night-vision application.