Tunable deep-blue luminescence from ball-milled chlorine-rich Cs(NH)PbClBr nanocrystals by ammonium modulation.

For the first time, a novel class of deep-blue (DB)-emitting Cs(NH)PbClBr (0.3 ≤ ≤ 1) perovskite nanocrystals (PNCs) were prepared by a facile ligand-assisted one-step ball milling method. The resulted PNCs are characterized by high chlorine content (66.7%) and excellent color purity. Their photoluminescence position can be finely modulated from 434 nm to 447 nm, which extends notably beyond the current Rec. 2020 color standard, by the NH content. Among them, Cs(NH)PbClBr shows the highest quantum yield close to 40%. The PNCs exhibit high phase and optical stability under ambient conditions and UV light according to the NH content. This work offers a new avenue to produce DB perovskites for future full-color displays and optoelectronics.