Observing Metallic Carriers in Highly Faceted Plasmonic Cd₂SnO₄ Inverse Spinel Nanocrystals

Abstract Correlating data from optical, structural, and theoretical methods allows the properties of highly faceted Cd₂SnO₄ (CTO) inverted spinel plasmonic semiconductor nanocrystals (PSNCs) to be fully evaluated. The use of Sn(II) in the colloidal reaction for CTO results in reproducible octahedral PSNCs with an aspect ratio of 1.30. Correlating extinction spectra with magnetic circular dichroism yields a carrier density (n = 5.19 × 10¹⁹ cm⁻³) and carrier effective mass (m* = 0.022m_e) respectively. ¹¹³Cd and ¹¹⁹Sn solid‐state NMR experiments show clear evidence of metallic‐like carriers in CTO NCs based upon the observation of Knight shifts. These data suggest that carrier formation in CTO arises from Sn antisite occupation of octahedral Cd sites (Sn_Cd)_. From a broader perspective, the results point to wide‐bandgap spinels as being an important but understudied class of plasmonic PSNCs.