Octahedral distortion in 2D perovskites may come from two primary interactions: the hydrogen bonding between octahedra and BA cations, and similarly, between octahedra and MA cations. By contrast, 3D perovskites, lacking an organic layer, depend solely on the interaction between MA cations and octahedra. Previous research has indicated that in 3D perovskites, octahedral tilting angles increase continuously with temperature. However, our findings show an opposite trend with a decrease in the average octahedral tilting angles, both equatorial and axial, as temperature rises, which is consistent with previous experimental observation on 2D perovskites. Such difference suggests that the interactions between the organic layer and octahedra play a more dominant role in octahedral tilting in 2D perovskites. Evidence of this is seen in the tilting of the terminal Pb-I bonds, which increases as the temperature decreases, as shown in Fig. and. The terminal bond tilting is primarily driven by the hydrogen bond interactions between terminal iodides and BA cations, which