Title : Direct photolithography of quantum dots via photoclick chemsitry for high-resolution QLEDs
Abstract:
Quantum dot light-emitting diodes (QLEDs) have emerged as pivotal candidates for next-generation displays, owing to their tunable emission wavelengths, narrow spectral bandwidth, high brightness, and solution-processability. However, achieving high-precision quantum dot (QD) patterning remains a critical bottleneck for industrial implementation. Conventional inkjet printing suffers from limited resolution (<5 μm) and coffee-ring artifacts, whereas traditional photolithography compromises QD performance during photoresist processing. Direct photolithography has recently emerged as an innovative approach to bypass these limitations by simplifying traditional photolithographic workflows. This methodology integrates QDs with photosensitive molecules, enabling efficient fabrication of ultra-high-resolution patterns with large-area uniformity while maintaining compatibility with semiconductor manufacturing protocols. Nevertheless, existing direct lithography techniques typically require stringent environmental controls and precise exposure parameters. Developing an air-processable direct lithography method compatible with large-scale semiconductor manufacturing therefore holds critical significance.
Leveraging photo-click chemistry's advantages of mild reaction conditions, high selectivity, and rapid kinetics, we propose a UV-triggered azide-alkyne cycloaddition strategy for QD patterning. Distinct from prior inert-atmosphere-dependent methods, our approach utilizes ambient air conditions with standard 365 nm UV irradiation, ensuring seamless integration with semiconductor fabrication lines. The reaction achieves efficient QD film crosslinking, enabling submicron-resolution patterning while preserving intrinsic optoelectronic properties. Notably, the crosslinked QD layers achieved a record external quantum efficiency (EQE) of 20.05% in QLED devices, attributed to suppressed interfacial defects and optimized charge balance. By synergizing click chemistry precision with semiconductor-grade manufacturability, we establish a universal platform for high-resolution optoelectronic patterning, accelerating industrial adoption of QLEDs and related quantum dot technologies.
We further extend this direct photolithography to functional layers including PEDOT:PSS and metal oxides (WOₓ, MoO₃). Through controlled photochemical processes involving crosslinking and ligand exchange, we achieved solubility modulation of these materials, enabling ultrahigh-resolution patterning exceeding 3,300 PPI. This advancement demonstrates compatibility with multilayer device architectures and addresses a critical challenge in RGB full-color QLED commercialization.
