The formation of coupled quantum dots CQDs may give an exceptional platform for sharp optoelectronic applications, bio labeling, and quantum information processing. Here in the present study, we report the formation pathway of different assemblies of heterostructures with CdSe and ZnS quantum dots (QDs) with a focus on the forming CQDs consisting of bicompartmental Janus structures (Structure consisting of two different compartments with the two unique QDs coupled). Doping quantum dots and combining dissimilar components together are two efficacious ways for modulating the optoelectronic and optical properties of quantum dots. For the first time, we have successfully synthesized Mn-doped ZnS-CdSe coupled quantum dots (CQDs) by combining above said two strategies together. Mn2+ doped ZnS quantum dots revealed outstanding intense photoluminescence with 4T1(4G) – 6A1(6S) transition. In the undoped CQD, the coupling between the individual QDs enhances the exciton lifetimes at 570 and 630 nm emission of bicompartmental JanusA with 36ns & 31ns and in bicompartmental JanusB with 41ns & 94.8ns, and Mn2+ doped ZnS-CdSe CQD further showed the improved lifetime in both bicompartmental JanusA and JanusB. Highly photoluminescent Mn-doped ZnS-CdSe coupled quantum dots (CQDs) have been prepared by a modified hot injection method. Mn2+ doped ZnS-CdSe CQD photoluminescence shows a quantum yield of 37%, which decays over a few micro-seconds, whereas the PL in undoped ZnS-CdSe CQD has a rather small quantum yield and decays predominantly in tens of nanoseconds. PL spectra of doped CQDs are remarkably Stokes shifted in comparison to the band edge.

Photodynamics of Mn2+ doped coupled quantum Dot ZnS-CdSe

ACS Spring 2022

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