Fig. 4: ZnS heteroepitaxy on InP NCs achieving improved uniformity in a single epilayer level.

a Schematic of conventional ZnS heteroepitaxy performed at high temperatures. Re-oxidation of the surface through Zn(OA)₂ inevitably introduces unreactive surface oxide, in turn, a non-uniform ZnS epilayer is generated. b Proposed fabrication protocol for uniform ZnS epilayer is composed of three stages: Stage I for oxide removal, Stage II for ZnS cluster saturation, and Stage III for ZnS epitaxial layer formation. In Stage II, alkyl chains of 1 and oleate ligand are visualised using grey diffusion cones. For other cases, the diffusion cone was omitted for conciseness. Low and high magnification (inset) dark-field transmission electron microscopy images of InP/ZnS NCs using InP–OA NCs with a size of 3.3 nm: c ~4 ZnS epilayers grown on re-oxidised InP NCs; d ~1 ZnS epilayer fabricated by (b); e ~4 ZnS epilayers prepared by (b). f PL decay dynamics of InP NCs with a size of 3.3 nm coated with different ZnS epilayer thicknesses: ~1 (light purple; size = 3.6 ± 0.4 nm), ~2 (purple; size = 4.7 ± 0.6 nm) and ~4 ZnS epilayers (deep purple; size = 5.6 ± 0.8 nm). Thickness-dependent PL QY values of InP/ZnS NCs are provided in the Inset. Source data are provided as a Source Data file.