Copper sulfide nanocrystals (Cu2-xS) are a class of plasmonic semiconductors whose tunable NIR plasmon absorption band has been very attractive for many applications, including photovoltaics,1 sensing,2 and phototherapy. 3 Copper sulfide's composition and resulting vacancy densities can vary with different synthetic conditions,2 oxygen exposure and aging,4 affecting the bandgap and the resultant free carrier concentration. The free carrier concentration, in turn, changes the localized surface plasmon resonances (LSPRs). We have expanded the methods to tune the LSPRs by showing that changing the surface passivation of Cu2-xS through ligand exchange reactions with different tetrafluoroborate salts can modulate the free hole density and alter the surface-dependent LSPRs and phase behavior of Cu2-xS. Different degrees of electron-withdrawing/donating ability of surface ligands can adjust the free hole density in Cu2-xS nanocrystals, thus modulating the LSPRs.

Tetrafluoroborate surface ligand affects on the plasmonic behavior of copper sulfide nanoparticles

256th National Meeting (2018)

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