Microfluidic acoustic micromixer enabling controllable synthesis of La³⁺-doped CsPbBr₃ perovskite nanocrystals

The continuous synthesis of doped halide perovskite nanocrystals under mild conditions remains challenging because conventional batch processes suffer from slow mixing and poor nucleation homogeneity. Here, we report an acoustically driven multichannel micromixer that achieves complete mixing within 3 ms at a flow rate of 1500 μL min^-1, enabling rapid and homogeneous precursor contact for the continuous synthesis of La-doped CsPbBr₃ nanocrystals. By independently controlling the La precursor input, nominal doping levels of 0%, 10%, 30%, and 50% were obtained under otherwise constant flow conditions. Structural characterization and defect-formation-energy calculations show that La preferentially substitutes at the Pb site, preserving the cubic perovskite lattice while inducing lattice contraction and local electronic reconstruction. Moderate La incorporation enhances steady-state emission, whereas higher doping levels prolong the excited-state lifetime from 47 to 103 ns and significantly improve thermal stability. Density functional theory calculations attribute these effects to conduction-band-edge reconstruction, charge redistribution, and shortening of local Pb/La-Br metal-halide bonds induced by La-for-Pb substitution. This work establishes acoustic micromixing as a controllable continuous-flow platform for the synthesis of doped halide perovskite nanocrystals and provides mechanistic insight into La-induced luminescence modulation and stability enhancement in colloidal CsPbBr₃ nanocrystals.