Direct Laser Writing of Micro–Nano Filters Based on Three-Photon Polymerization

Direct laser writing (DLW) enables the manufacturing of functional quantum dot (QD)-polymer nanostructures with the special performance desired for technological applications. However, most papers fabricate the QD-polymer photoresist based on the principle of two-photon polymerization using laser wavelengths of 750-800 nm, which cannot effectively fabricate the near-infrared QD-polymer photoresist with absorption wavelengths above 800 nm due to linear absorption. Moreover, most papers report a relatively low doping concentration of QDs. To address these issues, this study introduces three-photon DLW technology using a near-infrared 1035 nm laser to effectively avoid the linear absorption of the near-infrared PbS/CdS QD-polymer photoresist. Three kinds of QD-polymer photoresists with concentrations up to 150 mg mL^-1 are prepared through surface modification of QDs. We demonstrate that three-photon DLW is feasible to fabricate high-concentration QD-polymer photoresist to produce micro/nano high-performance QD-polymer filters of visible and near-infrared light absorption. This study provides materials and process guidance for the fabrication and application of visible and near-infrared optical filters through three-photon DLW processing of various kinds of functional nanoparticles-polymer photoresist.