Summarizing, for all quasi-2D HP systems, high-n phases emerge with increasing 3D composition ratios. For RP-type systems, higher-n or 3D-like phases emerge at the top surface when the heavier spacer cation is employed, which simultaneously suppresses the growth of low-n 2D HP kinetic products (e.g. n=2-4). In contrast, n=1 and/or 2 2D HPs are dominant at the bottom of the film matrices. DJ-type spacer BDA homogenizes the 2D phases along the vertical direction. However, it also manifests thinner 3D-like phases with broader thickness distributions, offering a larger bandgap with energetic inhomogeneities that impede efficient charge transport upon PV applications. ) BDA, (e,f) ThEA, (g,h) PEA, and (i,j) DPA, respectively.