Fig. 2. (a) Low-magnification TEM images of the initial Cs₄PbBr₆ NCs (average diameter 10 ± 1.5 nm) and fully-transformed CsPbBr₃ NCs (average edge length 8 ± 0.4 nm) after their reaction with PMAO in toluene. (b) XRD patterns of the initial Cs₄PbBr₆ NCs and of the partially- and fully-transformed ones. Top and bottom stick patterns are those of the reference bulk compounds: rhombohedral Cs₄PbBr₆ (pattern ID 04-015-9683, ICSD code 162158)27 and orthorhombic CsPbBr₃ (pattern ID 96-451-0746, COD code 4510745).28 The broad peak at ∼20° is due to PMAO. (c) Optical absorption (left panel) and emission (right panel) spectra of toluene solutions of initial Cs₄PbBr₆ NCs (blue curve), PMAO (orange curve), and partially- (black curve), and fully-transformed (green curve) NCs. The inset in the left panel shows photographs of the samples under excitation with a 365 nm lamp demonstrating visible green PL of partially- and fully-transformed NC samples.