Fig. 1: Surface-guided epitaxial CsPbBr3 nanowires on C-plane sapphire.
(a) An optical photoluminescence image of surface-guided nanowires and microwires emitting green luminescence during wide-field excitation with a blue (405 nm laser). The growth directions of the nanowires on the sapphire substrate are marked with blue indices and vectors. (b) Cross-sectional atomic-resolution STEM HAADF image taken in the \([11\bar 20]\) viewing direction of the sapphire substrate. The atomistic model overlay shows the atomic positions that are associated with the bright dots in the HAADF image. Detailed view of the atomic model (c) across and (d) along the growth axis of the nanowires. The yellow rectangles mark the repeat period (see also Supplementary Fig. 1 for a top-view of the epitaxial relations). e SEM image of nanowires with highly varying heights. (f–g) A typical tapered nanowire with a height gradient is displayed in 3D (f) and 2D (g) AFM images. (h) TEM image and EDS elemental map of a typical triangular cross-section. (i) Illustration of the shape, facets and growth direction of CsPbBr3 surface-guided nanowires.
