High‐efficiency,electrophosphorescent polymers with porphyrin–platinum complexes in the conjugated backbone: Synthesis and device performance

A series of soluble, conjugated, electrophosphorescent copolymers with (meso‐tetraphenylporphyrinato‐κ⁴N)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 dialkyl‐substituted fluorene monomers by a modified Suzuki coupling reaction. The study of the photoluminescence decay indicated that poly2,7‐(9,9‐dioctylfluorene)‐co‐2,12‐((meso‐tetraphenylporphyrinato‐κ⁴N)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. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4174–4186, 2006