Low-temperature phosphorescence and triplet exciton transport in 4-bromobenzophenone polymorphs

► Phosphorescence spectra of two polymorphs of 4-bromobenzophenone were measured at 1.6 K. ► The differences in the spectra are ascribed to differences in triplet exciton diffusivities. ► Within a 1D model based on crystal structures exciton bands were calculated for both forms. ► Phosphorescence data corroborate the inference that diffusion in the triclinic form is faster.