The luminescence excitation and emission spectra of the CdSe/Ln and ZnS/Ln [Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb] NPs are shown in panels (a)–(g), respectively. The electronic absorption spectra of the CdSe and ZnS NPs are also included in panels (a) and (b) for comparison. The shorter time decay kinetics of the ZnS and ZnS/Ln [Ln = Tb, Eu, Pr, Ho] to monitor the NP’s intrinsic depopulation rates are shown in panel (h). Panel (i) shows the longer time decay profiles of the CdSe/Ln and ZnS/Ln [Ln = Tb, Eu] NPs to monitor the Tb³⁺ and Eu³⁺ depopulation rates. Panel (j) shows the lifetime distribution analysis of the Tb³⁺ and Eu³⁺ emissions. (Adapted with permission from Reference [90], Copyright 2019 Elsevier).