Quantum Dots Facilitate 3D Two-Photon Laser Lithography.

In the past two decades, direct laser writing (DLW) technologies have seen tremendous growth. However, strategies that enhance the printing resolution and the development of printing material with assorted functionalities are still sparser than expected. In this paper, we present a cost-effective method to tackle this bottleneck. Semiconductor quantum dots (QDs) are selected to carry out this task, most importantly via surface chemistry modification to enable their co-polymerization with the monomers resulting in transparent composites. Our evaluations indicate that the QDs show great colloidal stability and their photoluminescent properties are well-preserved. This allows further exploration of the printing characteristics of such composite material. We show that in the presence of the QDs, the material provides a much lower polymerization threshold with faster linewidth growth, indicating that the QDs form a synergetic relationship with the monomer and the photoinitiator, widening the dynamic range of the material and thus increasing the writing efficiency for broader fields of applications. Lowering the polymerization threshold reduces the minimum achievable feature size by around 32%, which is well-matched with STED-based (i.e., stimulated-emission depletion microscopy) methods in writing 3D structures. We further elucidate the mechanism of the synergetic behavior, further guiding the future development of functional materials for DLW-related printing technologies. This article is protected by copyright. All rights reserved.