Assessing Photoinduced Carrier and Heat Transfer in Tin-Doped Indium Oxide Nanocrystals

Degenerately doped semiconductor nanocrystals exhibit tunable localized surface plasmon resonances with strong optical absorption cross sections and band gaps. Upon excitation, these materials produce non-equilibrium carrier distributions that rapidly relax, presenting a brief window for utilization. These features mark plasmonic nanocrystals as promising candidates for new applications that require efficient light absorption and highly directed energy and carrier utilization, such as photodetectors, photovoltaics, and photocatalysts, if we can understand and engineer efficient transport mechanisms. Here, we investigate hot carrier and heat transfer from prototypical tin-doped indium oxide (ITO) nanocrystals to adsorbates as a model system for harvesting and utilizing light in plasmonic semiconductor nanocrystals. Using transient absorption spectroscopy, we track carrier and energy transfer from ITO nanocrystals to adsorbates and evaluate the impact of aliovalent dopant concentration, wavelength, and energy level alignment. We find that these variables strongly impact carrier transfer to adsorbates. Utilizing local temperature reporters, we simultaneously quantify heat transfer from ITO nanocrystals into their environment. Combining these results, we suggest general design rules to optimize carrier energy transfer from plasmonic semiconductors.