In this work, a microfluidic system was applied to develop a simple, continuous, and stable method for producing CsPbBr3/Cs4PbBr6 complex NCs.

Technology Overview
In this work, we applied a microfluidic system for synthesizing CsPbBr3/Cs4PbBr6 NCs and optimized PLQY over 80%. The CsPbBr3/Cs4PbBr6 NCs obtained were used to deploy the printing ink with the mixed solvents of hexane and octane. High-resolution patterns were successfully printed, and a mini-LED was fabricated with this kind of perovskite ink.

Applications & Benefits
A large and high-resolution pattern could be printed with this ink, and this printing technology was successfully processed in the fabrication of mini-sized color-converted LEDs. The green emission of the demonstrated LED well obeyed the requirement of the Rec. This result demonstrated the great potential of our technique for the promotion of developing color-converted micro-LED displays in the future.

Abstract：
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.

Microfluidic synthesis of CsPbBr₃/Cs₄PbBr₆ nanocrystals for inkjet printing of mini-LEDs
Author：Bao Z., Luo J.-W., Wang Y.-S., Hu T.-C., Tsai S.-Y., Tsai Y.-T., Wang H.-C., Chen F.-H., Lee Y.-C., Tsai T.-L., Chung R.-J., Liu R.-S.
Year：2021
Source publication：Chemical Engineering Journal  Volume 426  130849
Subfield Highest percentage：99%    Industrial and Manufacturing Engineering    #3/33

https://www.sciencedirect.com/science/article/pii/S1385894721024347