High performance NIR-I to NIR-II emission of a Cr3+-doped Cs2NaLuCl6 phosphor with an IQE and EQE of up to 92.9% and 60.75%

We developed a Cr 3+ -doped Cs 2 NaLuCl 6 by a grinding–sintering method, which exhibited emission peaked at around 960 nm, with a FWHM of ∼182 nm, and the IQE and EQE of the optimized phosphor were as high as ∼92.9% and ∼60.75%, respectively.