Efficient and tunable photoluminescence for terbium-doped rare-earth-based Cs₂NaYCl₆ double perovskite

Lead-free double perovskite materials with efficient and stable self-trapped exciton (STE) emissions show enormous potential for next-generation solid-state lighting. However, the low-emission efficiency and difficulty of spectral regulation are two major obstacles to their application. Here, all-inorganic rare-earth-based double perovskite Cs₂NaYCl₆ single crystals with strong blue emissions were reported as effective hosts to accommodate lanthanide ion doping. By controlling the introduction of Tb^{3 +} ions and efficient energy transfer from the STEs to the dopants, the emission color of Cs₂NaYCl₆ single crystals was flexibly modulated from blue to green. The quantum yields were also significantly improved from 10% to 78.81% by optimizing the Tb^{3 +} ion concentration. Further, stable light-emitting diode prototypes based on Cs₂NaYCl₆ color conversion materials were fabricated to demonstrate the practical applications of rare-earth-based double perovskite.