Band Engineering-Tuned Localized Surface Plasmon Resonance in Diverse-Phased Cu2-xSySe1-y Nanocrystals

Cation-deficient copper chalcogenide nanocrystals (NCs) as a typical degenerated semiconductor have attracted great attention owing to their unique properties. However, the association between band structures and localized surface plasmon resonance (LSPR) in such NCs has not been thoroughly studied. Moreover, the synthesis of the colloidal Cu2-xSeyS1-y NCs with diverse crystal phases remains a challenge to date. Hence, we developed a facile method to synthesize a range of Cu2-xSeyS1-y-alloyed NCs with disparate crystal phases. We elucidated the tunable band structures and LSPR shift, and the results indicated that the modulation of the valance band maximum (VBM) position by Se/S alloying and the overlapping of the valence band and the Fermi level (E-F) dominate LSPR properties in alloyed NCs. Not only the variation of Cu vacancy along with the induced free carrier concentration but also the negative shift of VBM contribute to the LSPR shift toward higher energy.

Automated summary

Cation-deficient copper chalcogenide nanocrystals have unique properties and have attracted great attention. However, the relationship between band structures and localized surface plasmon resonance (LSPR) in these nanocrystals has not been thoroughly studied. This study developed a facile method to synthesize alloyed copper chalcogenide nanocrystals with different crystal phases and explored their tunable band structures and LSPR properties.