Thermally Modulated Microfluidic Fabrication of Phase-Tunable Cs4PbBr6/CsPbBr3 Hybrid Perovskite Nanocrystals for White Light-Emitting Diodes

Abstract

All inorganic CsPbBr3 perovskite nanocrystals (NCs) exhibit outstanding luminescence for optoelectronics, yet poor environmental stability severely restricts their practical deployment. As a stable derivative phase, Cs4PbBr6 can effectively improve structural stability. Nevertheless, the rational fabrication of high-quality Cs4PbBr6/CsPbBr3 hybrid NCs remains challenging owing to the lack of straightforward and scalable synthetic strategies. To overcome these hurdles, we synthesize well-defined Cs4PbBr6/CsPbBr3 hybrid NCs via a temperature-controllable continuous-flow microfluidic route. This platform precisely modulates phase composition via systematic temperature tuning across a range of 110–170 °C, producing distinct compositions from Cs4PbBr6-dominant to high-purity CsPbBr3. A direct correlation was elucidated between temperature-induced phase transformation and optical properties. The NCs synthesized at 130 °C exhibited a high photoluminescence quantum yield of 96.24% and bright 521 nm green emission. These NCs were successfully integrated into white light-emitting diodes incorporating a 478 nm blue excitation chip and K2SiF6:Mn4+ red phosphor, which demonstrated excellent color performance with a luminous efficiency of 86.3 lm W−1 and Commission Internationale de l’Éclairage coordinates of (0.2991, 0.3784). This work highlights the potential of continuous-flow microfluidics for precise phase modulation and scalable production of high-quality perovskite NCs, offering a viable route for advanced optoelectronic applications.