Highly Stable Perovskite Nanocrystal Patterns via Rheology-Controlled Microlithography

We present uniform PNC patterns that are highly stable in harsh environments (air, water, and high temperature (40 °C) with high relative humidity (90% RH)). These PNC patterns were produced by sequentially controlling the rheological behaviors of the PNC/siloxane nanocomposites. The first modification reduced its viscosity, allowing for the solution processing of the PNC/siloxane nanocomposites. The viscosity-controlled nanocomposites were spin-coated on a glass substrate, then a siloxane-resin-pinning (SRP) process was applied to increase the elastic behavior of the quasi-cured films. This process effectively prevented agglomeration and transition of the nanocomposites to a disordered bulk state, thereby maintaining the thin and uniform films. Finally, the films were optically patterned using UV exposure under a photomask. The resulting PNC/siloxane line patterns with a width of 100 μm maintained a stable photoluminescence quantum yield (PLQY) for over 100 days in both water and ambient air. Furthermore, this microlithography, in conjunction with the SRP process of viscosity-controlled PNC/siloxane nanocomposites, achieved the stacking of green-emitting patterns and red-emitting patterns on a blue-emitting microdisplay that exploits InGaN/GaN multi-quantum wells; this configuration achieved full-color white-emitting CC-LEDs in water. Moreover, we fabricate actual pixelated patterns of red-emitting and green-emitting PNC/siloxane nanocomposites directly on the micro-LEDs. The PNC/siloxane nanocomposite films also show a color conversion efficiency of 97.39% and convert blue light to green without blue-cutting color filter. These results demonstrate the potential of PNC/siloxane nanocomposites as both quantum dot enhancement films (QDEF) and quantum dot color conversions (QDCC) in displays.
Acknowledgement
This research was supported by the Digital Research Innovation Institution Program Through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (RS-2023-00283597).