Drawing on the hypothesis concerning the AIE properties of molecules featuring an 8π electron structure, several hexatomic and heptatomic ring molecules meeting this criterion indeed exhibit AIE properties. As shown in Figure , Yuan et al. discovered a hexatomic ring AIE molecule with a symmetrical oxygen atom substitution , which exhibits a π-electron structure similar to the previously double COT ring molecule proposed by Iyoda which possesses a twisted core and a benzene ring as a conjugated connecting skeleton. As depicted in Figure , the PL intensity in pure THF solution is very weak, but it is significantly enhanced after aggregation in 10:90 (v/v) THF/water, which emits bright yellow-green fluorescence. Chi et al. reported the first RIV-type AIE molecule which also possesses thermally activated delayed fluorescence (TADF) property with an 8π electron structure using phenothiazine as a twisted skeleton (as shown in Figure ). The compound shows high emission efficiency (Φ=93.3%) and delayed fluorescence in the aggregated state.