Hierarchical Gradient Black Matrix Cavities: Enabling Superior Inkjet‐Printed Quantum‐Dot Color Conversion Pixels for Micro‐LED Displays

ABSTRACT

Quantum‐dot color conversion (QDCC) enables high‐fidelity, wide‐gamut Micro‐LED displays, yet the black matrix (BM) confinement severely affects inkjet‐printed QD pixel performance. The morphology, surface interactions, and optical properties of the BM directly dictate the droplet positioning, drying dynamics, and final luminescence performance of the QD films, respectively. These factors collectively lead to nonuniform QD distribution, whereas the optical properties of the BM mainly determine the luminescence performance of QD films. Here, we propose a hierarchical gradient black‐matrix architecture (HG‐BMA) with graded sidewalls to topographically confine inkjet‐printed QDCC pixels, restraining capillary flow and contact‐line pinning and greatly improving QD coverage uniformity and color conversion stability. Dodecyltrimethoxysilane (DTMS) hydrophobizes the substrate and sidewalls, raising glass contact angles from 17.7° to 84.4° and photoresist angles from 47.6° to 92.5°. With six print passes into the HG‐BMA, we successfully fabricated the Micro‐LED pixels with a 4.5 µm‐thick QDCC layer, featuring an ultralow blue‐light transmittance of only 0.198%, a light conversion efficiency of 19.5% (representing a 32.3% improvement over conventional architectures), and a color purity exceeding 91% for color conversion of Micro‐LEDs. This HG‐BMA offers a scalable high‐precision inkjet printing route toward wide‐gamut next‐gen Micro‐LED displays.