Printable and Stable Microlens‐Type Perovskite Quantum Dot Color‐Converting Resin Through Rheology Control for Efficient and Reliable Micropatterning for Full‐Color Displays

Perovskite quantum dots (PQDs) are promising color‐converting materials for full‐color micro‐light‐emitting diode (micro‐LED) displays; however, PQDs have intrinsic poor stability which hinders practical applications. In addition, micro‐LEDs that incorporate color‐converting layers with reliable operation remain limited. Herein, we report a highly‐stable thixotropic PQD‐based color converting resin (thixo‐PQD resin) by precise control of rheological properties and robust matrix encapsulation. Fumed silica nanoparticles (FSNs) are incorporated in thixo‐PQD resin that serve as thixotropic and scattering agents, thereby forming microlens thixo‐PQD arrays (ML thixo‐PQD arrays). The resulting ML thixo‐PQD arrays retain high photoluminescent quantum yield (PLQY ∼ 78%) in ambient air, under 85°C/85% RH, and under continuous blue‐light irradiation for > 2400 h. This stability of the ML thixo‐PQD array arises from synergistic effects of (i) effective physical blocking of water and oxygen by the FSN network and encapsulating matrix and (ii) chemical interactions between the PQD surface ligands and the encapsulating matrix. To confirm the feasibility as a color‐converting layer on micro‐LED, we print ML thixo‐PQD arrays directly onto blue‐emitting micro‐LED backplanes; the devices achieve a 59.2% increase in luminous flux and reliability under 85°C/85% RH for > 60 d. These thixo‐PQDs have potential application in high‐resolution, full‐color micro‐LED displays.