Polarization‐Induced Quantum Confinement of Negative Charge Carriers by Organic Nanoporous Frameworks

Abstract We characterize the attachment of excess‐electrons to organic nanoporous systems such as molecular nanohoops and models of covalent organic frameworks (COFs) using many‐body methods. All the nanopore systems exhibit diffuse electronic states where the excess‐electron is bound to the molecular scaffold via long‐range polarization forces, and the excess‐electron is predominantly localized in the interior of the nanopore or away from the molecular scaffold. Such “nanopore‐bound” states show an enhanced electron‐transfer coupling compared to more strongly‐bound skeletal‐states (or valence‐bound states), where the excess‐electron is confined to the molecular skeleton. For 1D assemblies of nanohoops, the bands formed from nanopore‐bound states have a consistent nearly‐free‐electron character, indicating an efficient excited‐state pathway for charge‐carriers, while the bands from skeletal‐states have higher effective mass along certain lattice directions. The nanopore‐bound states show distinct size‐dependent variations in electron affinities compared to skeletal‐states and previously observed molecular quantum corral states. We conclude that nanopore‐bound states emerge from polarization‐induced quantum confinement, forming a distinct common feature of organic nanoporous matter with potential for efficient electron‐transport.