Multiple and distinct lanthanide (Ln)-doped nanoparticles (NPs) can benefit in accessing multiplex assays for photoluminescence-based applications. This study develops Tb− Eu co-doped ZnS nanoparticles (NPs) using different synthetic pathways. These include Zn(Tb)S/Eu, Zn(Eu)S/Tb, Zn(TbEu)S, and ZnS/TbEu NPs, where the lanthanides within parenthesis and after a slash indicate their addition synthetically and postsynthetically, respectively. The differing synthetic protocols affect the dopant concentrations and spatial location in the NPs, which give rise to remarkable differences in interdopant electronic interactions. Both charge trapping-and spectral overlap-mediated interdopant electronic interactions can explain energy transfer from Tb 3+ to Eu 3+ . Control experiments with Tb−Yb, Tb−Sm, and Tb−Tm containing NPs identify the importance of the relative energetics of the Ln 2+ ground energy level with respect to the Tb 3+ luminescent energy level in controlling the Tb 3+ −Ln 3+ interaction, thus implicating the importance of charge trapping-mediated interdopant electronic interactions. The results discussed provide a solid foundation to identify suitable codoped NP luminophores.

Postsynthetic modification of inorganic nanoparticles (NPs) involving appropriate cation pairs at or near ambient conditions can exchange their spatial positions. The characterization of final products from these reactions although attracted...

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This work investigates the tuning of electronic interaction between excited Tb3+ (Tb3+*) and Eu3+ by varying the excitation wavelengths, which consist of different electronic origins spanning the entire range of excitation spectra. Direct excitation bands of trivalent lanthanide cations (Ln3+) are accessed in the Ln-doped calcium fluoride, Ca(Ln)F2, nanoparticles (NPs). The experimental outcomes from the NPs are compared to that in the bulk solvent with freely floating entities. Remarkable excitation wavelength-dependent Tb3+–Eu3+ electronic interaction is observed in the NPs, with 370 nm excitation of Tb3+ being found to provide the optimum energy to maximize the Eu3+ emission. This excitation energy dependence is found to be less prominent in the bulk medium. Different mechanisms for Tb3+–Eu3+ electronic interaction are argued to be operative in the confined NP and bulk environments. The energy transfer efficiency from Tb3+* to Eu3+ in NPs can be maximized by (i) sole excitation of Tb3+ and (ii) maintaining the energy difference between the excitation energy and the Eu2+ ground energy level in the range of 4500–7500 cm–1. Additionally, we suggest the necessity of concomitant consideration of the steady-state and time-resolved response of both Tb3+ and Eu3+ emissions to decipher the Tb3+* → Eu3+ electronic interactions, instead of considering a single parameter to gauge such a process. These findings collectively provide important insights to design Tb–Eu-containing luminophores for their potential use in multiplex assays.