Efficient Hot Thermal Carrier Transfer in Plasmonic Metal Oxide Nanocrystals

Harnessing hot carriers in plasmonic nanoparticles provides a new paradigm for nonequilibrium photodetectors, photocatalysts, and photothermal technologies. Here, we show that the low carrier concentration in plasmonic Sn4+:In2O3 (ITO) nanocrystals enables a new platform for hot carrier generation and extraction via hot thermal carriers rather than hot 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 electron-electron scattering time. Modelling the process with Marcus theory and a two temperature model reveals that the hot thermal carrier transfer can exceed hot athermal carrier transfer at rates of absorption. These data reveal clear guidelines for designing plasmonic nanomaterials for hot thermal carrier generation and transfer, paving the way for new hot carrier technologies.