Fig. 1: Scheme representation of dynamic coupling in host–guest RTP systems.
From: Building bridges through dynamic coupling for organic phosphorescence
a Historical development of RTP mechanism in host−guest systems. b Static model and spectral characteristics in previous RTP work. Either host or guest molecules (or both) were firstly excited to the singlet state, followed by possible transfer of excitons through a ‘ghost’ intermediate state to the triplet state of guest, activating RTP of guest emitter. Only fluorescence of host and guest, as well as phosphorescence of guest were observed in the spectra. All species, including host, guest and ‘ghost’ complex, were static and remained unchanged throughout the photophysical process. c Dynamic coupling model and spectral characteristics in this work. Upon excitation of the host molecules, the collision between host and guest molecules formed a spectroscopically ‘visible’ complex, which subsequently dissociated to activate the RTP of guest. Such a dynamic complex with enhanced intersystem crossing (ISC) ability worked as a bridge to transfer excitons from the singlet state of host to the triplet state of guest and could be observed in the spectra. FH, fluorescence of host; FG, fluorescence of guest; LC, emission of complex; PG, phosphorescence of guest. Blue spheres represented host molecules, and red for guest molecules. Gray arrows represented UV excitation. The dotted curved arrows represented ISC process of complex.
