Direct Writing High-Resolution Quantum Dot Micro-Patterns: Toward High-Performance Electroluminescence Behavior
Min Zhang1,2, Ran Sun1,2, Zheng Xiao1,2
1State Key Laboratory of Bioinspired Interfacial Materials Science, School of Nano Science and Technology, Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, P. R. China.
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The fabrication of quantum dots (QDs) micro-patterns, especially those with both µm-scale high-resolution and mm-/cm- scale large area uniformity, remains a bottleneck limiting the application of quantum dot light-emitting diodes (QLEDs). Current strategies have suffered from either low resolution or complicated micro-template assisted fabrications deteriorating the device performance. Here, we developed a new conceptual high-resolution QDs micro-pattern with a linewidth of merely 2 µm in an area of ∼10 cm2 by a template-free direct writing strategy, featured as the distinguishable QDs micro-line array by the periodical nanoscale thickness difference. The enhanced capillary flow accelerates QDs deposition at each tri-phase contact line in a positive feedback manner until the liquid film breaking, which proceeds uniformly across the whole printing area in a good periodicity. Thus, a periodic conformal complementary QDs/PMMA heterostructure bilayer film, composed of alternate thick-QDs/thin-PMMA and thin-QDs/thick-PMMA unit, was constructed as the light-emitting layer, which facilitates the autonomous charge distribution at both inter- and intra- interface. The as-developed high-resolution micro-patterned QLED shows an external quantum efficiency as high as 21.4% even at a linewidth of 2 µm. The result offers a low-cost facile strategy for making large-area high-resolution micro-patterned QLED devices.
