Correlation between surface state and band edge emission of white light ZnxCd1−xS nanocrystals

Abstract

In this study, we have demonstrated a facile thermal pyrolyzed route to prepare ternary Zn_xCd_1−xS nanocrystals (NCs) with high quantum yield (QY) and white light emission. The detailed surface and structural characterizations based on the X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) measurements have illustrated that by controlling the Zn content, the surface chemical states as well as the surface state emission of NCs can be manipulated, and their optical properties can be tuned accordingly The Zn shell of NCs may enhance the surface state emission, especially for Zn_0.8Cd_0.2S, thereby promoting the white light emission and increasing the QY to 56%. Moreover, the QY of Zn_0.8Cd_0.2S decreases from 56 to 49% after aging in hexane for 2 months, implying that the stability of NCs is excellent. The surface oxide-rich structure could be the reason that influences the surface state emission and stability of the Zn_xCd_1−xS NCs.