Unveiling the Optical Properties of Micropattern-Based Fluorescent Gold Nanoclusters and Plasmonic Nanoparticles in Polymer Thin Films

Gold nanoclusters (Au NCs) and gold nanoparticles (Au NPs) are directly created within a polymer matrix by employing a direct laser writing (DLW) technique. The excitation of a continuous-wave 532 nm laser inside a hybrid metal complex/photoresist material optically induces a localized thermal effect, resulting in the formation of polymeric voxels containing either strongly fluorescent Au NCs, or plasmonic Au NPs, depending on the exposure dose. Furthermore, this DLW technique allowed us to fabricate multidimensional micropatterns of Au NCs within a polymer matrix by controlling the movement of the laser focus, achieving a feature size of 1 μm and a minimum periodicity of 1.5 μm. The direct creation of Au NCs and/or Au NPs inside a photoresist film offers a simple and low-cost approach for advancing the field of plasmonic nanofabrication and opens applications such as Au fluorescence-based lasers or Au quantum dots for quantum light generation.