Chemically Tunable, All-Inorganic-Based White-Light Emitting 0D-1D Heterostructures

In this study, one-dimensional (1D) Mn2+-doped ZnS (ZnS:Mn) nanowires (NWs) are initially created with a unique optical signature. Specifically, these nanostructures couple (i) ZnS defect-related self-activated emission spanning from wavelengths of 400-500 nm with (ii) Mn2+ dopant-induced emission centered at approximate to 580 nm. These doped ZnS nanostructures are initially fabricated for the first time via a template-based coprecipitation approach followed by a postsynthesis annealing process. Novel 1D-0D heterostructures are subsequently formed, incorporating ZnS:Mn2+ NWs and 2-amino-ethanethiol (AET)-CdSe quantum dots (QDs), by assembling annealed ZnS:Mn2+ NWs with AET-capped CdSe QDs as building blocks via a simple technique, involving physical sonication and stirring. Optical analyses of the heterostructures are consistent with charge (hole) and energy transfer-induced quenching of ZnS self-activated emission coupled with hole transfer-related quenching of Mn2+ emission by the QDs. The CdSe QD emission itself is impacted by competing charge (electron) and energy transfer processes occurring between the underlying ZnS host and the immobilized CdSe QDs. Chromaticity analysis reveals the significance of controlling both QD coverage density and Mn2+ dopant ratios in predictably influencing the observed color of our all-inorganic heterostructures. For example, white-light emitting behavior is especially prominent in composites, simultaneously characterized by (i) a 2.22% Mn2+ doping level and (ii) a molar compositional ratio of [ZnS:Mn2+]:[AET-capped CdSe QDs] of 1:1.5. Moreover, using these independent chemical knobs, it is possible to reliably tune for a significant shift within the composites from cold-white (9604 K) to warm-white (4383 K) light emission.