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 ) ions doped Cs M(In Sb )Cl (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 M(In Sb )Cl NCs can break the forbidden of f-f transition of Ln , thus increasing their radiative transition rates and simultaneously boosting the energy transfer efficiency from host to Ln . Finally, the wide-coverage NIR LEDs based on Sm , Nd , Er -tridoped Cs K Rb (In Sb )Cl NCs are fabricated and employed in the multiplex gas sensing and night-vision application.