Microfluidic-Based Patterning of High-Resolution, Uniform Luminescent, and Low Optical Crosstalk Quantum Dot Arrays for Full-Color Micro-LED Displays

Quantum dot (QD) color conversion layers (CCLs) present an economical and reliable approach to achieve full-color micro-LED displays. Microfluidic technology demonstrates significant advantages for patterning and integrating multicolor QDs, including high precision, rapid processing, low material consumption, and low fabrication costs. However, preparing high-resolution CCLs with low optical crosstalk remains challenging due to limitations in microfluidic chip design induced by swelling of polydimethylsiloxane (PDMS) microchannels in nonpolar solvents utilized for QD dispersion. In this study, we developed a QD solution with a polymer additive that effectively suppresses PDMS swelling, making injection of QD solution into small-sized PDMS microchannels on chromium-patterned microhole glass substrates possible. The resulting QD CCLs exhibit high luminescence uniformity and a high resolution of 1285 ppi, with a subpixel dimension of 5 μm × 5 μm, which is the smallest dimension reported for CCLs fabricated by microfluidic technology. Furthermore, our innovative integration of chromium-patterned microhole glass substrates within a microfluidic device provides unprecedented optical isolation, effectively eliminating intersubpixel crosstalk in CCLs. By integrating optimized red and green QD CCLs with a blue GaN micro-LED array, we successfully fabricated a full-color micro-LED prototype with a resolution of 600 ppi and a wide color gamut of 115% NTSC. Owing to their high resolution, uniform luminescence, and low optical crosstalk, the proposed microfluidic technology holds significant promise for advancing next-generation full-color micro-LED displays.