Crosslinkable Siloxane Induced Direct Patterning of Highly Stable Halide Perovskite Nanocrystals

High resolution patterning of color conversion layers (CCLs) is essential for the demonstration of color converting light-emitting diodes (LEDs). Conventional color converting materials such as organic phosphor and inorganic quantum dot (QD) so far suffer from low color purity and high materials cost. Metal halide perovskite nanocrystals (PNCs) have been regarded as a promising color converting material in CCLs due to their high absorption coefficient, spectrally narrow light, easy color tuning, low materials cost, and high photoluminescence quantum efficiency (PLQE). However, the instability of PNCs in thermal treatment and in polar solvents limits its high resolution patterning through consequent photolithography process and its long-term stability in various condition. To enable low-cost direct patterning without using a high polarity photoresist and improve the stability of patterned PNCs, we here introduce the direct optical patterning of crosslinkable siloxane resin/PNC composite. Multicolored patterning of PNCs in micrometers was demonstrated by siloxane resin pinning (SRP) process which mitigate the high viscosity and concomitant shrinkage problem in the siloxane/PNC composites. The patterned PNCs showed stable photoluminescence quantum efficiency (PLQE) in harsh liquid environments (e.g., in water, acid, or base solutions, and in various polar solvents), which provide the breakthrough into high density PNC-based micro-LED.