Self-Confined Precipitation of Ultrasmall Plasmonic Cu2–x Se Particles in Transparent Solid Medium

Integration of plasmonic nanostructures into solid-state devices is a crucial step to realize nanophotonic applications. In addition to colloidal assembly and nanofabrication processes such as electron-beam lithography, it is also possible to directly precipitate plasmonic nanoparticles (NPs) from solid transparent media, but it currently remains limited to a few noble metal-based systems. Herein, we show that plasmonic Cu2–x Se NPs with an ultrasmall size (∼2 nm) can be precipitated from a borosilicate glass matrix through a self-confinement solid-state reaction between Cu+ and Se2–. The near-infrared (NIR)-localized surface plasmon resonance (LSPR) energy of the resultant plasmonic glasses is tunable by proper control of the reactions. The strong NIR-LSPR broadband of the Cu2–x Se NPs endows the plasmonic glass with a strong nonlinear optical (NLO) response, which is characterized by excitation power-dependent nonlinear absorption behavior. The intriguing NLO properties of the plasmonic glass doped with Cu2–x Se NPs may enable immediate applications such as optical switches and optical limiters.