Magnetophotoluminescence line-shape narrowing through interactions between excited states in organic semiconducting materials

We find that interactions between intermolecular excited states can cause a line-shape narrowing in magnetophotoluminescence in an organic composite containing N,N-dimethylaniline and pyrene in the liquid state. The line-shape narrowing indicates that interactions between intermolecular excited states can decrease the spin-exchange interaction within intermolecular excited states. Our analysis shows that interactions between intermolecular excited states can occur through long-range Coulomb interaction, midrange spin-orbital interaction, and short-range spin interaction, with the consequence of line-shape modification in the development of magnetic field effects. Our experimental results reveal a parameter, the interactions between intermolecular excited states, involved in the development of magnetic field effects in organic semiconducting materials.