Phosphine-Free, Highly Emissive, Water-Soluble Mn:ZnSe/ZnS Core–Shell Nanorods: Synthesis, Characterization, and in Vitro Bioimaging of HEK293 and HeLa Cells

Abstract

Phosphine-free, highly luminescent one-dimensional Mn2+ ion-doped ZnSe(core)/ZnS(shell) nanorods (NRs) were synthesized by heating-up method (core) followed by hot injection route (shell). Effect of Mn2+ doping and shell thickness on structural and optical properties is reported. The NRs were formed with wurtzite-structured Mn:ZnSe core (diameter 2.52 nm) encapsulated epitaxially by a wurtzite-structured ZnS shell (thickness of 3.51 nm) with 3.1% lattice mismatch that alters the band alignment of the overall core–shell structure. A redshift was observed in optical absorption and photoluminescence (PL) emission due to an overall size increase with increasing shell thickness. Because of the reduction of defects/traps by surface passivation, the maximum photoluminescence quantum yield (QY) was obtained to be 49.35%. The exciton radiative lifetime for the core–shell NRs (1.678 ms) was more prolonged than that of the core (0.573 ms). A clear dependence of QY and lifetime was established on the Mn2+ content and...