The molecular materials with structures of luminescent core and peripheral carrier groups （e.g. carbazoles）, have exhibited high-performance in organic light-emitting diodes （OLEDs）. Present work is to understand the basic process of electronic and energy exchange between the peripheral functional groups and the central core through quantum chemical analysis. As an example, 4,7-bis（9,9-bis（6-（9H-carbazol-9-yl）hexyl）-9H-fluoren-2-yl）benzo[c]- [1,2,5]thiadiazole （TCBzC） is investigated in regards to optoelectronic properties using density functional theory （DFT）. The results suggest that the forbidden transition from peripheral carbazole to the central chromophore core makes for separated electrical and optical properties, and high performance electroluminescence （EL） is mainly at- tributed to the energy-transfer from carbazoles to the fluorene derivative core.
