Using Suzuki polycondensation, we have synthesized polyhedral silsesquioxane-tethered polyfluorene copolymers, poly(9,9'-dioctylfluorene-co-9,9'-bis[4-(N,N-dipolysilsesquioxane)aminop henyl]fluorene) (PFO-POSS), that have well-defined architectures. This particular PFO-POSS molecular architecture increases the quantum yield of polyfluorene significantly by reducing the degree of interchain aggregation; in addition, these copolymers exhibit a purer and stronger blue light by preventing the formation of keto defects.