Preparation and Fluorescence Properties of Aqueous Soluble Thiourea Modified ZnSe:Cu Quantum Dots

Abstract

Aqueous phase Cu doped ZnSe (ZnSe:Cu) quantum dots (QDs) stabilized with mercaptopropionic acid were prepared, and thiourea was used as a surface modifier to obtain core-shell ZnSe:Cu/ZnS QDs. QDs had a sphalerite structure, were uniformly dispersed, had an average particle size of approximately 5 nm and an emission peak at around 460 nm. After thiourea modification, a wide band-gap ZnS shell was coated on the QDs to passivate the surface, reduce surface states, and significantly improve fluorescence intensity. Thiourea modified ZnSe:Cu/ZnS QDs exhibit better surface passivation, fluorescence efficiency, and stability than those of other surface modifiers like Na2S and thioacetamide. Quantum yields were further improved after UV irradiation eliminated surface dangling bonds.

Preparation of ZnSe Quantum Dots by Hydrothermal Method Assisted by Ammonia

“…The intrinsic fluorescence of ZnSe QDs is in the range from near ultraviolet to blue, and fluorescence of doped ZnSe QDs is in the range of loner wavelength [6~9] . For example, Cu doped ZnSe QDs emission green light and Mn-doped ZnSe QDs emit yellow, orange and red light [6][7][8][9] . Because of nontoxicity and brand emission range, ZnSe QD is expected as a good candidate in biological and medical application.…”