Controlled Synthesis of Cu2- xSe Nanoparticles as Near-Infrared Photothermal Agents and Irradiation Wavelength Dependence of Their Photothermal Conversion Efficiency.

The ability to manipulate the near-infrared (NIR) localized surface plasmon resonance absorbance of copper chalcogenide materials is of utmost importance for applications such as photothermal therapy (PTT). In this work, we manipulate the NIR absorbance of copper selenide (Cu2- xSe) nanoparticles (NPs) by precisely controlling their size and composition. We also introduce a facile method for transferring ultrasmall hydrophobic Cu2- xSe NPs into aqueous solution. We then elucidate the relationship between the irradiation wavelength and photothermal conversion efficiency for these materials. The resulting insights can advance the use of copper chalcogenide nanomaterials in PTT applications.