Direct patterning and optical properties of quantum dot films based on UV micro-LEDs

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Quantum dots (QDs) are advanced nanomaterials with tunable optical properties.
• Micro light-emitting diodes (micro-LEDs) are key components in modern display technologies.
• Combining QDs with micro-LEDs offers a pathway for enhanced color conversion.

Purpose of the Study:

• To investigate the optical properties of QD films patterned on micro-LEDs.
• To evaluate the impact of multi-layer QD films on color conversion efficiency.
• To improve the performance of QD-micro-LED devices by mitigating light leakage.

Main Methods:

• Fabrication of multi-layer QD films with various colors.
• Direct patterning of QD films onto micro-LEDs using maskless photolithography.
• Optical characterization under 405 nm micro-LED excitation.
• Implementation of distributed Bragg reflectors (DBRs) to reduce substrate light leakage.

Main Results:

• 3-layer QD films demonstrated superior photoluminescence intensity and absorption ratios.
• Initial 3-layer QD films showed high power conversion efficiency (PCE) but were limited by light leakage.
• Application of DBRs significantly enhanced PCE, average conversion ratios, and photoluminescence quantum yields (PLQYs) for all colors.

Conclusions:

• Multi-layer QD films are effective for color conversion in micro-LED applications.
• DBR integration is crucial for overcoming light leakage and maximizing the optical performance of QD-micro-LED devices.
• The optimized QD-micro-LEDs with DBRs show substantial improvements in efficiency and quantum yield.