A series of soluble, conjugated, electrophosphorescent copolymers with (meso-tetraphenylporphyrinato-kappa N-4)platinum(II) (PtTPP) complexes incorporated into the polymer main chain were synthesized through the copolymerization of narrow-band-gap monomeric porphyrin-platinum(II) complexes and wide-band-gap dialkylsubstituted fluorene monomers by a modified Suzuki coupling reaction. The study of the photoluminescence decay indicated that poly[2,7-(9,9-dioctylfluorene)-co-2,12((meso-tetraphenylporphyrinato-kap pa N-4)platinum(II))] (PFO-PtTPP) was a triplet emitter. The electroluminescence emission from the fluorene segment was completely quenched for copolymers with PtTPP contents as low as 0.5 mol %. The PFO-PtTPP copolymers emitted deep red light. The device based on the porphyrin-platinum(II) copolymer PFO-5PtTPP (with 5 mol % PtTPP in the copolymer) showed the highest external quantum efficiency of 1.95% with an emission peak at 684 nm in an indium tin oxide/poly(3,4-ethylenedioxythiophene)/polyvinylcarbazole (PVK)/70:30 (w/w) PFO-5PtTPP: 2-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole/Ba/Al device configuration. In comparison with the PFO-PtTPP copolymers synthesized via a postpolymerization metalation route, copolymerization from Pt metal complexes proved to be a more efficient synthetic route for high-efficiency electrophosphorescent polymers. (c) 2006 Wiley Periodicals, Inc.