An Interpretation of Delayed Fluorescence Behavior of Naphthalene in Biphenyl Host in the Lower Temperature Region

Temperature and concentration dependences of the delayed luminescence observed in the naphthalene (guest)–biphenyl (host) mixed crystal system have been studied. The presence of the temperature-independent delayed fluorescence (TIDF) and its significance in the evaluation of activation energy have also been confirmed in this system as in the case of the benzo[f]quinoline–biphenyl system previously reported, and the generality of the existence of TIDF as well as its significance in relation to activation energy has been suggested. In addition, some remarks have been made on the nature of TIDF and the decay behavior.