Physical insights into the facilitation of an unprecedented complexation reaction on the surface of a doped quantum dot leading to white light generation

Herein, we report a complexation reaction between Zn2+ ions present on the surface of an orange-red-emitting environmentally sustainable Mn2+-doped ZnS QD and a non-emitting copper quinolate (CuQ2) complex, which leads to the formation of a greenish blue-emitting surface zinc quinolate (ZnQ2) complex. The synchronous contribution of the surface ZnQ2 complex and Mn2+-doped ZnS QD is directed towards the generation of photostable bright white light (at λex – 355 nm) with chromaticity coordinates of (0.34, 0.42), color rendering index (CRI) of 71 and color-correlated temperature (CCT) of 5046 K. The ZnQ2 complexed Mn2+-doped ZnS QD is herein called as quantum dot complex (QDC). The excitation- and time-dependent tunability in emission, chromaticity, CRI and CCT of QDC revealed their futuristic applications in light-emitting devices with an anticipated color output. The current work also shows the catalytic behavior of Mn2+-doped ZnS QDs towards facilitating the formation of surface ZnQ2 from CuQ2, which is not feasible with regard to the reactivity of CuQ2 under normal conditions according to the Irving–William series. The rate of the reaction was observed to be first order with respect to CuQ2 at 20 °C, and the complexation constant for the formation of ZnQ2 was estimated to be 8.3 × 105 M−1. This is important for understanding the surface chemistry of metal chalcogenide QDs towards complexation reactions.