Figure 2.

(a) High-resolution TEM image of Cs₃Bi₂Cl₉ QDs; (b) high-resolution TEM image of Cs₃Bi₂Cl₉:Ce 30% QDs; (c) particle size distribution of Cs₃Bi₂Cl₉ and Cs₃Bi₂Cl₉:Ce 30% QDs; (d) Raman spectra of Cs₃Bi₂Cl₉ and Cs₃Bi₂Cl₉:Ce 30% QDs. The upper part: the red line is the experimental data of the sample doped with 30% Ce, and the other color lines are single-peak fitting, The lower part: the black line is the experimental data of undoped samples, and the other color lines are single-peak fitting.