Full-Color Micro-LED Display Enabled by Highly Stable Photo-Patternable Perovskite Quantum Dot Resin

In the field of micro-light-emitting diodes (LEDs), perovskite quantum dots (PQDs) have emerged as promising materials for color conversion layers (CCLs) with high stability and high luminescence performance. However, to achieve high photoconversion efficiency, CCLs having a sufficiently thick structure need to be fabricated, which is challenging using common spin-coating techniques. Moreover, although compositing with a polymer increases the atmospheric stability of PQDs, their limited dispersibility in polymer matrices affects the photoluminescence efficiency. To circumvent these issues, in this study, we used a squeegee patterning method to fabricate PQD CCLs with a sufficient thickness and photopatternability for micro-LED displays. A PQD/siloxane resin composite in which PQDs exhibited excellent dispersibility in the siloxane matrix was obtained without damaging the PQD structure by activating the PQD surface using an anion salt followed by modification with a silane ligand and sol–gel condensation. The introduction of silane ligands in the PQDs enabled the preparation of PQD/siloxane composites without aggregation and with superior atmospheric stability compared with PQD CCLs prepared via conventional inkjet or vacuum-drying processes. Furthermore, PQDs convert the blue light emitted from blue micro-LEDs to red and green light, enabling RGB full-color display without additional transfer-printing process for red and green micro-LEDs. Using this highly ambient stable PQD/siloxane composite as CCLs, a full-color micro-LED display was constructed. In addition, the use of a flexible and thin black matrix mold allows fabricating a flexible micro-LED display that can be operated without damage even under a bending radius of 5 mm.