Fig. 2: The optical characterization for the Eu³⁺ doped CsPbCl₃ PeNCs with K⁺ ion co-doping.

a Absorption spectra (dashed line) /emission spectra (color solid line) of Eu³⁺ doped CsPbCl₃ PeNCs with various K⁺ ion doping concentrations and the emission spectra (gray solid line) of CsPbCl₃ PeNCs with various K⁺ ion doping concentrations. b, c Bandgap of the PeNCs and the corresponding PLQY, energy transfer efficiency of Eu³⁺ doped CsPbCl₃ with increasing the K⁺ ion-concentration. d The dependence curves of the overlap integral J(λ) and exciton center wavelength λ in theoretical and experimental, respectively. e Critical binding distance (R₀) of Eu³⁺ doped CsPbCl₃ with increasing the K⁺ ion-concentration