On-Demand Sintering of Gold Nanoparticles via Controlled Removal of o-Nitrobenzyl Thiol Ligands Under Record-Low...

Metal nanoparticles-based nanoinks have shown potential for fabricating metallic components essential to the realization of innovative 3D-printed electronic devices. However, fabricating metallic patterns on flexible, heat-sensitive substrates remains challenging due to high temperature and high energy sources, such as intense pulsed light (IPL), involved in the sintering process. Here an efficient sintering method is presented using ultralow power UV by leveraging the photocleavable ligand, o-nitrobenzyl thiol (NT), - functionalized gold nanoparticles (AuNPs). The controlled removal of NT ligands upon UV irradiation enhances light absorption by reducing the filling factor of voids in the printed layer, increasing the layer temperature, and facilitating further ligand desorption. This positive feedback mechanism accelerates nanoparticle sintering at several orders of magnitude lower energy than IPL, achieving an electrical conductivity of 7.0 × 10⁶ S m^-1. This nanoink promises the parallel printing of multimaterial components through ultralow power photonic sintering for fabricating multifunctional 3D-printed electronic devices.