Double channel emission from a redox active single component quantum dot complex

Abstract

Herein we report the generation and control of double channel emission from a single component system following a facile complexation reaction between a Mn²⁺ doped ZnS colloidal quantum dot (Qdot) and an organic ligand (8-hydroxy quinoline; HQ). The double channel emission of the complexed quantum dot-called the quantum dot complex (QDC)-originates from two independent pathways: one from the complex (ZnQ₂) formed on the surface of the Qdot and the other from the dopant Mn²⁺ ions of the Qdot. Importantly, reaction of ZnQ₂·2H₂O with the Qdot resulted in the same QDC formation. The emission at 500 nm with an excitation maximum at 364 nm is assigned to the surface complex involving ZnQ₂ and a dangling sulfide bond. On the other hand, the emission at 588 nm—with an excitation maximum at 330 nm—which is redox tunable, is ascribed to Mn²⁺ dopant. The ZnQ₂ complex while present in QDC has superior thermal stability in comparison to the bare complex. Interestingly, while the emission of Mn²⁺ was quenched by an electron quencher (benzoquinone), that due to the surface complex remained unaffected. Further, excitation wavelength dependent tunability in chromaticity color coordinates makes the QDC a potential candidate for fabricating a light emitting device of desired color output.