White-light-emitting Cu,Mn co-doped Zn-In-S/ZnS quantum dots with high stability and their electroluminescence

We developed a facile noninjection synthetic method to prepare white light-emitting Cd-free thick shell Cu,Mn:Zn-In-S/ZnS quantum dots (QDs) with high stability. Based on systematic research on the relationship between shell thickness and QD stability, it was demonstrated that overcoating thick ZnS passivation layers (similar to 7.9 monolayers) onto a Cu, Mn: Zn-In-S core could improve the photoluminescence quantum yield (PL QY) substantially up to 75% and the high PL QY could be maintained after the initial oil-soluble QDs were transferred into aqueous media via ligand exchange. The PL lifetime of thick shell Cu, Mn: Zn-In-S/ZnS QDs increased remarkably by 30-fold (from 0.13 ms to 3.50 ms). Also, the prominent thermally and photochemically stable properties of the resultant thick shell QDs have been ascertained. Moreover, gram-scale white emission Cu, Mn: Zn-In-S/ZnS QDs could be prepared in a single batch reaction via the noninjection synthetic approach. In addition, the as-obtained white emissive Cu, Mn: Zn-In-S/ZnS QDs could be employed in white quantum dot light-emitting diode (QD-LED) devices and have shown good performance with a lower turn-on voltage of 5.7 V and color rendering indexes (CRI) as high as 85, indicating that Cu, Mn: Zn-In-S/ZnS QDs could be a potential candidate in QD-based lighting or solid-state lighting as a single color-converting material.