The results of the line shape analyses by the above SLE are shown in Figure where the 𝑘 LMC values for TAB are described. 𝑘 LMC =130 ns -1 in the bulky 3 TAB* molecule suggests that the rotation of triplet excitons is due to intramolecular triplet-exciton hopping in a much shorter timescale than the molecular rotation dynamics observed in the small molecule of 3 DPA*. As the molecular rotation of DPA is suppressed by increasing viscosity (Figure ), the 𝑘 LMC value of TAB is also small in the T:P = 1:19 solvent (Figure ), indicating that the intramolecular exciton hopping is hindered. Notably, the distorted molecular geometry of TAB in the triplet state is characterized by a shorter distance (0.72 nm) between the two anthracene moieties (where the exciton resides) than the other longer distances (0.79 nm) between the other anthracene unit (Figure ). Therefore, the distances between these anthracene moieties must be altered significantly for the triplet-exciton to hop within the molecular framework (Figure ). This structural change is anticipated to be suppressed when the bulky paraffin molecules surround 3 TAB*, resulting in the inhibited exciton hopping with the slow entire molecular rotation.