Revealing the roles of in-plane and out-of-plane van der Waals interactions in modulating the dimension-dependent ground- and excited-state properties of quasi-1D zigzag COFs

van der Waals (vdW) interactions dictate the properties of low-dimensional materials, yet the role of in-plane interactions, and especially the synergy between in-plane and out-of-plane vdW forces, remains largely unexplored. Using first-principles and nonadiabatic molecular dynamics calculations on quasi-one-dimensional porphyrin COFs with a zigzag boundary, we show how these dual vdW interactions modulate structural, electronic, and excited-state properties. In-plane vdW interactions minimally impact ground-state structures but suppress low-frequency vibrations and decrease nonadiabatic coupling due to the unique zigzag interface, extending the excited-state lifetime from 2.1 ns (1D) to 21.3 ns (2D). This behavior persists in other quasi-1D systems with identical interfaces but vanishes in configurations featuring non-zigzag interfaces. In the 3D architecture, distinct stacking modes lead to marked variations in interlayer coupling strength, tuning the lifetime from 2.7 to 29.6 ns. This work unravels the complex correlation between in-plane/out-of-plane vdW interactions, establishing critical design principles for tailored low-dimensional vdW materials.