Fig. 5: The PL evolution in different-structured NCs.

a–c Variation of luminescence enhancement factor (orange lines) and lifetime (baby blue lines) of Eu³⁺ in different NCs under 273 nm light excitation, through Gd³⁺–Eu³⁺ energy transfer. d–f Luminescence enhancement factor (purple lines) and lifetime (baby blue lines) of Eu³⁺ in different NCs under 395 nm light excitation. g–i Normalized I_E/I_M value of Eu³⁺ in different NCs.