Efficient Plasmon-Induced Hot Thermal Carrier Transfer in Plasmonic Metal Oxide Nanoparticles

Harnessing hot carriers in plasmonic nanoparticles provides a promising paradigm for nonequilibrium photodetectors, photocatalysts, and photothermal technologies. Here, we show that the low carrier concentration in plasmonic Sn⁴⁺:In₂O₃ (ITO) nanocrystals enables efficient hot carrier generation and extraction via hot thermal carriers rather than athermal carriers. Using transient absorption spectroscopy, we measure hot carrier generation and transfer between ITO nanocrystals and Rhodamine B (RhB) adsorbates following infrared plasmonic excitation. Pump and fluence dependent experiments show that charge transfer arises from hot thermal carriers, which are efficiently generated due to ITO's low electron heat capacity and short electron-electron scattering time. Modeling the process with Marcus theory and a two-temperature model reveals that the hot thermal carrier transfer can exceed athermal carrier transfer at high rates of absorption. These data reveal clear guidelines to design plasmonic nanomaterials for hot thermal carrier generation and transfer.