One-Step Synthesis of Pure CsPbBr ₃ Quantum Dots: Precise Size/Phase Tuning for Blue-Green Emission

Conventional methods for phase structure tuning and sizing of CsPbBr3 quantum dots (QDs) usually involve multistep procedures and are susceptible to impurity contamination. In this study, we propose a simplified thermal injection strategy that can simultaneously control the crystal size (8.9 to 17.5 nm) and phase transition as well as maintain high crystallinity by precisely adjusting the Cs+ concentration. Notably, a systematic increase in Cs+ content induces a reversible monoclinic-cubic-monoclinic phase transition with tunable quantum confinement effects. Comprehensive characterization results show that the luminescence wavelength could be tuned from 510 to 524 nm (blue-green color illumination), while the cubic-phase CsPbBr3 QDs possess the highest luminescence peak intensities, with photoluminescence quantum yields as high as 74.84% and extended exciton lifetimes (43.12 ns) due to the reduction of surface defects. The optimized cubic phase features a narrow size distribution (σ = 9.9%), high color purity (CCT = 10,575 K), and enhanced emission intensity, which are directly related to its symmetric crystal structure. The carrier dynamics during photoexcitation were also studied by using femtosecond transient absorption spectroscopy. The luminescent dot array was also well prepared through a dispensing process. The above results show that our simple method is helpful in the large-scale production of high-quality perovskite quantum dots for applications in display.