The CsPbBr3 and Cs4PbBr6 NCs dispersed in toluene were examined via transmission electron microscopy (TEM) (Figures and). The average diameter of the CsPbBr3 and Cs4PbBr6 NCs is 8 ± 1.09 nm and 14 ± 3.06 nm, respectively. The calculated particle size distribution is presented in Figures and, Supporting Information (SI). The lattice fringes spacing is 0.26 nm and 0.40 nm, corresponding to the (301) and (104) crystallographic planes of orthorhombic CsPbBr3 and rhombohedral Cs4PbBr6, accordingly (insets of Figures and). The X-ray diffraction (XRD) patterns of the CsPbBr3 and Cs4PbBr6 NCs are presented in Figure . For CsPbBr3 NCs, the diffraction pattern corresponds to the orthorhombic phase. For Cs4PbBr6 NCs, the XRD pattern corresponds mainly to the rhombohedral phase. However, a small amount of the cubic CsPbBr3 phase is present, as indicated by the peaks at 22.42˚. This coexisting phase of CsPbBr3 in Cs4PbBr6 was previously reported. To understand the impact of polar solvents on the structural integrity and morphology of CsPbBr3 and Cs4PbBr6, we disperse the NCs in the EtOH/Toluene mixture. Here, the NCs were dispersed in two different concentrations: EtOH: Toluene (1:7) and (1:1.4) ratio (named solutions 1 (Sol. 1) and 2 (Sol. 2), respectively). The XRD pattern for CsPbBr3 and Cs4PbBr6 NCs in Sol. 1 and 2 remained the same (Figure ). However, the peak intensities for the NCs dispersed in Sol. 2 were significantly lower. This phenomenon can be ascribed to the partial decomposition of the NCs in the presence of a high concentration of EtOH. The TEM images presented in Figure (SI) illustrate that the morphology of the NCs dispersed in Sol. 1 remains consistent with those dispersed in pure toluene. Contrarily, the NCs dispersed in Sol. 2 are mostly decomposed due to the high EtOH concentration, SI Figures .