To verify the crystalline phase of the materials, we collected WAXS images from the same suspensions we obtained the SAXS data shown in Figure to 2d. The WAXS data (Figure ) agree with the orthorhombic crystalline phase of perovskites and present some insights on the growth directions of the nanoplates. While in SAXS curves we observe the diffractions of {101} planes, in WAXS data, we observe the diffractions from the {202} planes and beyond. In Figure , the diffractions whose Miller indexes are (040) and ( ) are convoluted for all the samples; this is also true for the (020) and (101) (Figure and Figure ). When the sample thickness decreases (e.g., from I-170 to I-110 samples), the ratio between the diffractions (0k0):(h0l) decreases, and the (0k0) peak shifts to lower-Q values (Figure and Figure ), suggesting that the thickness is in the [0k0] direction. Hence, the {h0l} planes are likely perpendicular to the plane of the PNPls, and, therefore, their respective diffractions are not affected by the thickness reduction. This analysis can be extended to the CsPbBr3 samples as well. A representation of a CsPbBr3 PNPl is shown in Figure .