The structure-dependent quantum yield of ZnCdS nanocrystals

Abstract

In this study, we demonstrate the effect of atomic arrangement and valence band structures on the optical properties of Zn_xCd_1−xS nanocrystals (NCs) by controlling the Zn ratios. Our results indicate that the increase in coordination number of Zn–O bonding within the NCs and the structural changes in the valence band (VB) would enhance their quantum yield (QY) due to the influence of the surface states and charge recombination rate in VB, respectively. Consequently, the Zn_xCd_1−xS NCs with an optimal x = 0.4 have the highest QY of about 56%. By combining structural and optical analysis, we systematically elucidate the effect of composition on the local structure and the charge distribution in the VB of the Zn_xCd_1−xS NCs. Thus, this study provides mechanistic insight into the development of ZnCdS NCs with high QY.