Intermolecular Electron Delocalization

This lecture explores how intermolecular interactions influence the delocalization of electrons on the material scale, focusing on pi-conjugated molecules packing closely in the solid state, resulting in electronic coupling and molecular orbital interactions. The instructor explains how these interactions lead to molecular orbital splittings, narrowing the Homo-Lumo gap and forming band-like structures, as illustrated with the example of pentasyn. The lecture emphasizes the reduction of the band gap to enable charge carrier promotion and the potential for charge transport in crystalline organic semiconductors. The importance of dispersive and quadrupole interactions in optimizing molecular packing is highlighted, ultimately affecting the material's electronic properties.