Investigation of compositionally tunable localized surface plasmon resonances (LSPRs) of a series of indium tin oxide nanocrystals prepared by one-step solvothermal synthesis

A series of novel nonmetallic plasmonic materials, indium tin oxide (ITO) nanocrystals (NCs), with tunable doping ratios of tin (from 0 up to 25%), were synthesized through a one-step solvothermal method. Cubic-shaped NCs with good crystallinity and uniform-size distribution (17nm), for all doping ratios, were confirmed through the X-ray diffraction patterns and transmission electron microscopy images. As inferred from X-ray photoelectron spectroscopy and inductively coupled plasma measurements, Sn is preferentially distributed close to the surface of ITO NCs. In particular, localized surface plasmon resonances (LSPRs) were tuned from near- to mid-infrared regions only by varying the doping ratios, which is of interest, for example, to avoid high-loss levels associated with metallic nanoparticles in LSPR biosensing applications. Our work provides a series of reliable and accessible materials for the researchers who need different wavelengths of LSPR frequencies in near-infrared and/or mid-infrared regions. It will benefit the research and development of nonmetallic plasmonic materials in a wider application scope.