Tunable dual-emission of Sb³⁺, Ho³⁺Co-doped Cs₂NaScCl₆single crystals for light-emitting diodes

Lead-free halide double perovskites are considered as one of the most promising materials in optoelectronic devices, such as solar cells, photodetectors, and light-emitting diodes (LEDs), due to their environmental friendliness and chemical stability. However, the extremely low photoluminescence quantum yield (PLQY) of self-trapped excitons (STEs) emission from lead-free halide double perovskites impedes their applications. Herein, Sb³⁺ions were doped into rare-earth-based double perovskite Cs₂NaScCl₆single crystals (SCs), resulting in a large enhancement of PLQY from 12.57% to 87.37%. Moreover, by co-doping Sb³⁺and Ho³⁺into Cs₂NaScCl₆SCs, the emission color can be tuned from blue to red, due to an efficient energy transfer from STEs to Ho³⁺ions. Finally, the synthesized sample was used in multicolor LED, which exhibited excellent stability and optical properties. This work not only provides a new strategy for improving the optical properties of Cs₂NaScCl₆SCs, but also suggests its potential application in multicolor LEDs.