Convenient and large-scale synthesis of high-quality, all-inorganic lead halide perovskite nanocrystals for white light-emitting diodes

We report a convenient and large-scale process for the preparation of CsPbX₃ (X = Cl, Br, I) nanocrystals (NCs) using stable and inexpensive olive oil to replace oleic acid as a surface treatment reagent. The obtained NCs show bright photoluminescence with absolute photoluminescent quantum yields of up to 93% and a tunable emission wavelength ranging from 409 to 689 nm. More importantly, the controllable morphology (nanocubes, nanorods, and nanospheres) of CsPbI₃ NCs can be tuned by varying the reaction temperature, which may be ascribed to multiple organic ligands in olive oil that influence the growth/nucleation of the NCs. A white light-emitting diode (WLED) device was demonstrated by combining the green-emitting CsPbBr₃ NCs and red-emitting K₂SiF₆:Mn⁴⁺ phosphors with a blue LED chip. Under operation with a 3 V forward bias voltage, the optimized WLED exhibits a high color rendering index of 85, a luminous efficiency of 46 lm/W, and a color gamut of 118% NTSC through a color filter.