Controlled growth of lead-free cesium zirconium halide double perovskite nanocrystals through a microfluidic reactor.

Vacancy-ordered CsZrX (X = Cl, Br) double perovskite nanocrystals (NCs) have recently attracted increasing attention in optoelectronic applications due to their promising photoluminescence property, high photostability, and low toxicity. However, their ultra-fast reaction limits the growth control and kinetics study of these CsZrX NCs. Here we report the synthesis of CsZrX NCs through a microfluidic reactor and achievement of tunable emission wavelengths by controlling the NC size and hybrid halogen ions. Reaction kinetics study reveals that the amine ligand and reaction temperature play dominate roles in the growth and optical performance of the CsZrX NCs. The effects of flow rate, precursors, and ligand ratio on the morphology and optical property of the NCs were also investigated. This study provides an insight into the growth kinetics of the CsZrX perovskite NCs and their continuous production through a microfluidic reactor that could facilitate the development and optical application of lead-free vacancy-ordered double perovskite NCs.