LAUSR

Abstract Molecular photophysical properties are not only related to the basic structures but also affected by their packing modes. In this work, excited state properties of two isomeric Cu complexes (Complex 1 and Complex 2) with aggregation induced emission (AIE) and thermally activated delayed fluorescence (TADF) features are theoretically studied. The surrounding environments for molecule in solution and solid phase are considered by polarizable continuum model (PCM) and the combined quantum mechanics and molecular mechanics (QM/MM) method respectively. In addition, the intermolecular interaction and intramolecular interaction are visualized by the reduced density gradient (RDG) function. Our investigations show that the geometrical changes between ground state (S0) and lowest singlet excited state (S1) are hindered in solid phase by the restricted intramolecular rotation (RIR) effect, which brings smaller Huang-Rhys factors. Moreover, the decreased reorganization energy from solution to solid phase, is mainly contributed by the reduction of dihedral angle in low frequency (