To better elucidate the nature of the intramolecular triplet-exciton hopping in TAB, we examined the temperature dependence of the EPR spectra. TREPR measurements of the PtOEP/TAB system were conducted (Figure ) in the T:P = 1:1 solvent from 240 K to 290 K. 𝑘 LMC values were determined by the line shape analysis (Figure ). In this temperature range, where TET from PtOEP proceeds efficiently, the EPR spectra of TAB are prominently influenced by the motional narrowing, resulting in a single peak at all temperatures. The temperature dependence of 𝑘 LMC for each system was analyzed using the Arrhenius equation of Eq. ( ) and the Eyring equation, Eq. ( ):