Figure 12.

(a) Schematic flowchart of CPC. TEM images and (inset) histograms of the particle size distribution of (b) CaS:Eu²⁺, Sm³⁺, Mn²⁺ and (c) functionalized CaS:Eu²⁺, Sm³⁺, Mn²⁺. (d) HRTEM of CaS:Eu²⁺, Sm³⁺, Mn²⁺. The inset shows the SAED pattern. (e) Excitation (1 – green line, left), PeL emission (2 – purple line, right), and up-conversion emission (3 – red line, right) spectra. The inset shows photographs of CaS:Eu²⁺, Sm³⁺, Mn²⁺ under UV (left) and NIR excitation (right). λ_em = 610 nm, λ_exc = 355 nm (PeL) or λ_exc = 980 nm (UC). Reproduced from [227] with permission from The Royal Society of Chemistry.