Blue Emitting CsPbBr3: High Quantum Confinement Effect and Well-Adjusted Shapes (Nanorods, Nanoplates, and Cubes) toward White Light Emitting Diodes

Controlled nucleation and slow growth endow blue emitting CsPbX₃ nanocrystals (NCs) with bright photoluminescence (PL), which is crucial needed in luminescent devices. In this paper, a low-temperature injection synthesis method is developed to control nucleation and the growth process by decreasing the reaction rate of ions, thereby controlling the morphologies of CsPbX₃ NCs in clusters, nanorods (NRs), nanoplates (NPLs), and nanocubes by adjusting precursors, ligands, and injection parameters. CsPbX₃ NCs exhibit excellent PL properties such as high quantum confinement effect. The PL peak wavelengths of CsPbBr₃ NPLs and NRs are at 451 and 467 nm, respectively, in which their full width at half maximum (FWHM) of PL spectra is 22 and 12 nm, while their PL efficiencies are 65 and 74%, respectively. The method is further used to create CsPbI₃ and CsPbCl₃. CsPbI₃ NPLs and NRs reveal PL peaks at 590 and 600 nm and PL efficiencies of 56% and 60%, respectively. These NCs exhibit excellent stability against ultraviolet light irradiation. A color conversion layer for white light-emitting diodes is fabricated using these highly bright NCs. A Commission Internationale d'Eclairage color coordinate of (0.31,0.33) is located at the white light region specified by Rec.2020 standard, and the color temperature reaches 6189 K.