Continuous and controllable synthesis of CsxPbyBrz-based perovskite nanocrystals by a microfluidic system

All-inorganic perovskite CsPbBr 3 shows great potential in optoelectronic device applications due to their excellent optoelectrical properties. However, its practical use is still dauntingly plagued by the poor stability. Recently, its derivatives Cs 4 PbBr 6 and CsPb 2 Br 5 featured with good stability and the versatility in crystal structure have emerged as promising alternatives. Nevertheless, synthesizing such a series of perovskites through a facile, scalable, and high-yield method is challenging, and their luminescence mechanisms are still elusive. Herein, we reported a facile and rapid method for continuous synthesis of Cs x Pb y Br z -based perovskites (including Cs 4 PbBr 6 , CsPbBr 3 /Cs 4 PbBr 6 , CsPbBr 3 , CsPbBr 3 /CsPb 2 Br 5 , CsPb 2 Br 5 ) via a microfluidic system. The transformations of different dimensional perovskite nanocrystals were realized by simply adjusting the precursor flow rate. CsPbBr 3 /Cs 4 PbBr 6 and CsPbBr 3 /CsPb 2 Br 5 composite nanocrystals exhibited bright emissions in their solid forms, where CsPbBr 3 nanocrystals uniformly embedded in Cs 4 PbBr 6 or CsPb 2 Br 5 matrix. Simultaneously, strong green fluorescence exclusively from CsPbBr 3 nanocrystals was detected and related energy transfer in composite nanocrystals was further investigated. Finally, the highly stable CsPbBr 3 /Cs 4 PbBr 6 nanocrystals were used for the construction of WLED with a wide color gamut of 131% NTSC. This work provides a novel path for large-scale and controlled synthesis of the ternary Cs-Pb-Br materials for specific light-emitting applications.