Abstract
Eu-doped ZnS quantum dots (QDs) have been synthesized by wet-chemical method and found to form in zinc blende (cubic) structure. Both Eu2+ and Eu3+ doped ZnS can be controllably synthesized. The Eu2+ doped ZnS QDs show broad photoluminescence emission peak around 512 nm, which is from the Eu2+ intra-ion transition of 4f6d1 – 4f7, while the Eu3+ doped samples exhibit narrow emission lines characteristic of transitions between the 4f levels. The investigation of the magnetic properties shows that the Eu3+ doped samples exhibit signs of ferromagnetism, on the other hand, Eu2+ doped samples are paramagnetic of Curie-Weiss type. The incident photon to electron conversion efficiency is increased with the Eu doping, which suggests the QD solar cell efficiency can be enhanced by Eu doping due to widened absorption windows. This is an attractive approach to utilize benign and environmentally friendly wide band gap ZnS QDs in solar cell technology.
Highlights
During the past decades, advances in the preparation and characterization of the II–VI semiconductor quantum dots (QDs) have revealed new physics in reduced dimensions and provided possibilities of fabricating novel materials.[1,2,3,4] ZnS is a ubiquitous semiconductor that has been studied widely as an important phosphor for optoelectronic and energy applications due to its better chemical stability and environmental friendliness compared to other chalcogenides.[5,6] On the other hand, ZnS’s wide band gap limits its use as a sensitizer in quantum dot sensitized PV solar cells
The incident photon to electron conversion efficiency is increased with the Eu doping, which suggests the QD solar cell efficiency can be enhanced by Eu doping due to widened absorption windows
It can be clearly seen that all the diffraction peaks of QDs can be well indexed as the zinc blende phase structure of ZnS, which are consistent with the standard card (JCPD No 65-9585)
Summary
Eu-doped ZnS quantum dots (QDs) have been synthesized by wet-chemical method and found to form in zinc blende (cubic) structure. Both Eu2+ and Eu3+ doped ZnS can be controllably synthesized. The incident photon to electron conversion efficiency is increased with the Eu doping, which suggests the QD solar cell efficiency can be enhanced by Eu doping due to widened absorption windows This is an attractive approach to utilize benign and environmentally friendly wide band gap ZnS QDs in solar cell technology.
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