Understanding Aggregation-Induced Emission in Molecular Crystals: Insights from Theory

Aggregation-induced emission can often be explained via the restriction of intramolecular rotation paradigm and/or excimer formation. The enhanced luminescence recently observed for aggregates of fluorenone derivatives are no exception. In this work, however, we use a recently developed excited-state electrostatic embedding technique to demonstrate that enhanced emission in diphenylfluorenone can be rationalized by considering a single-molecule process, in which the field induced by the crystalline environment at the excited state enhances the relative brightness of otherwise poorly emissive states, resulting in both enhanced fluorescence and a substantial bathochromic shift in comparison with emission in dilute solution.