Intensely Fluorescent π‐Stacks With High‐Efficiency Exciton Diffusion

Aromatic fluorophores typically exhibit significant fluorescence quenching upon π‐stacking aggregation, significantly limiting their applications in advanced luminescent materials. Although recent studies have reported intense excimer emission in select π‐stacking architectures, the underlying photophysical mechanisms remain unclear. In this study, we design a series of biomimetic membranes with rationally engineered π‐stacking interlayers that exhibited intense excimer/exciplex emission. These aggregates are found to display enhanced photoluminescence quantum yields (PLQYs) due to efficient exciton diffusion within the π‐stacks. This exciton migration process further enables efficient energy transfer to embedded acceptor dopants, resulting in both red‐shifted and enhanced emission. Our study provides a robust approach for assembling conventional aromatic fluorophores into high‐performance organic luminescent materials featuring high PLQY, large Stokes shift, and broadly tunable emission.