Enhanced Quantum-Confined Stark Effect in Sc3N@Ih-C80 Fullerene Dimers Via Intermolecular Coupling.

The modulation of molecular excited states and luminescence properties by external electric fields provides a fundamental physical basis for developing tunable optical and quantum functional devices at the molecular scale. In this work, density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were employed to investigate the electric-field response of the quantum-confined Stark effect (QCSE) in a covalently [2 + 2] cycloaddition-bridged Sc3N@Ih-C80 endohedral metallofullerene dimer. The results showed that, compared with the monomer, covalent bridging significantly enhances the electric-field tunability of energy levels. In the low-to-moderate field regime, the response is mainly governed by the polarizability term, whereas stronger fields promote electron-hole separation and exciton evolution from a Frenkel to a charge-transfer type. These findings elucidate the underlying physical mechanism of electric-field regulated excited states in assembled endohedral metallofullerene dimers and provide theoretical guidance for the design of molecular-scale optoelectronic and quantum devices.