Ultra-stable, Solution-Processable CsPbBr3-SiO2 Nanospheres for Highly Efficient Color Conversion in Micro Light-Emitting Diodes

Micro light-emitting diodes (??-LEDs) coupled to color conversion phosphors are among the most promising technologies for future display and artificial light sources. However, current emitters suller from excessively large particle sizes, preventing micron-scale processability, and/or low stability that hampers the device lifetime. Here, we demonstrate down-conversion ??-LED phosphors based on CsPbBr3 perovskite nanocrystals directly grown inside perfectly sealed mesoporous silica nanospheres (NSs). Key for this advancement is a high-throughput calcination procedure in the presence of K2CO3 as selective pore sealing agent, which simultaneously produces the CsPbBr3 nanocrystals, boosts their emission efficiency to >87%, and perfectly isolates them from the outer environment without causing inter-particle cross-linking or aggregation. This results in size-homogeneous, finely solution-dispersible, ultra-stable, and highly emissive CsPbBr3-SiO2 NSs that fit the technological requirements of photolithographic inks for highly uniform ??-LED color conversion patterns with pixels smaller than 20 ??m.

Automated summary

We have developed down-conversion ??-LED phosphors by growing CsPbBr3 perovskite nanocrystals directly inside sealed mesoporous silica nanospheres. The calcination process, in the presence of K2CO3, allows for the production of CsPbBr3 nanocrystals with high emission efficiency and isolation from the external environment. The resulting CsPbBr3-SiO2 nanospheres are highly stable, emissive, and dispersible, making them suitable for photolithographic inks for uniform ??-LED color conversion patterns with small pixels.