An Examination of the Cs 2 NaInCl 6 Luminescence: Interplay of Self‐Generated In + and Doped Sb 3+ , Er 3+ /Yb 3+ Ions

ABSTRACT This work introduces a novel explanation of the visible (Vis‐) and near‐infrared (NIR) Cs 2 NaInCl 6 luminescence based on spontaneously formed In 3+ →In + and a doping method by utilizing Er 3+ /Yb 3+ and Sb 3+ ions. A combined experimental and theoretical approach has been used to investigate the characteristics of the microcrystals, synthesized through precipitation and hydrothermal techniques. These yielded cubic, Sp.Gr. , or tetragonal structure, Sp.Gr. I 4/ mmm , depending on the dopants. In + (5 s 2 ) has provoked wide photoluminescence (PL) from ∼400–800 nm, and Sb 3+ (5 s 2 ) incorporation has greatly enhanced PL at 450 nm. While Er 3+ doping has enabled intense NIR emission (∼1540 nm), Yb 3+ sensitization not only improves Er 3+ PL in the 520–550 nm range (green light) but also adds a band at 980 nm. For Er‐doped, RE/Sb‐codoped Cs 2 NaInCl 6 , it is possible to observe not only downconversion but also upconversion (UC) emissions in the 520–550 nm range. DFT calculations have elucidated the dopant and vacancy effects on the band structure and luminescence behavior of the samples. Stable and simple in preparation phosphor‐converted LED prototypes have been constructed and characterized in the Vis‐ to NIR ranges.