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 Tb3+ 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 Tb3+ 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.