Microfluidic synthesis of CsPbBr₃/Cs₄PbBr₆ nanocrystals for inkjet printing of mini-LEDs

Zero-dimensional Cs₄PbX₆ (X = Cl, Br, I) perovskite material is recognized as a potential luminescent material and host owing to its excellent optical properties. However, the synthesis of large-scale CsPbBr₃/Cs₄PbBr₆ complex nanocrystals (NCs) is difficult, and their application in mini- or micro-LEDs remains limited. Herein, we applied a microfluidic system for a simple, continuous, and stable synthesis of CsPbBr₃/Cs₄PbBr₆ NCs. The CsPbBr₃/Cs₄PbBr₆ complex NCs were obtained after the optimization of the Cs/Pb precursor ratio and alkaline environment, and their photoluminescent quantum yield is up to 86.9%. These as-synthesized CsPbBr₃/Cs₄PbBr₆ NCs were used to produce a luminescent ink with the optimization of different solvents. This ink was successfully used to print large and high-resolution patterns, and fabricated mini-sized color-converted LED. The narrow green emission of the LED well obeyed the requirements of the Rec. 2020 standard, demonstrating the potential of this material in the inkjet printing applications of color-converted mini- or micro-LED arrays.