title: 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 Mn(2+) 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 Mn(2+) 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 Mn(2+) dopant. The ZnQ2 complex while present in QDC has superior thermal stability in comparison to the bare complex. Interestingly, while the emission of Mn(2+) 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.
authors.affiliation: Department of Chemistry and ‡Centre for Nanotechnology, Indian Institute of Technology Guwahati , Guwahati-781039, Assam, India.
authors.forename: Satyapriya
authors.initials: S
authors.lastname: Bhandari
authors.forename: Shilaj
authors.initials: S
authors.lastname: Roy
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Pramanik
authors.forename: Arun
authors.initials: A
authors.lastname: Chattopadhyay