Synthesis and Properties of Main-Chain Phosphorescent Polymer with Iridium Complex

Abstract

The main-chain phosphorescent polymers, PFCzIr(PhStz) and PFOIr(PhStz) with iridium complex (4-BrPhBt)₂Ir(Pytz), are synthesized by the Suzuki polycondensation, in which the fluorene-carbazole and fluorene segments are used as a polymer backbone. The studied photoluminescent and electroluminescent properties demonstrate good overlap of the emission spectra of poly(fluorene-carbazole) (PFCz) or polyfluorene (PFO) host and the absorption spectra of the iridium complex guest that meets requirements for the efficient Forster transfer from the host polymer to the iridium complex in polymers. With the increase of the content of iridium complex, the host emission intensity decreases, while the guest emission intensity gradually increases. As compared with PFOIr(PhStz), host-guest system in PFCzIr(PhStz) is more efficient in Forster energy transfer, and the photoluminescence and electroluminescence properties are more sound. Among all polymers, PFCzIr(PhStz) 5.0 demonstrates the best performance in electroluminescence, its fluorescence quantum is 22.74%. The devices fabricated from PFCzIr(PhStz)5.0 exhibit yellow-red emission with a maximum brightness of 1568 cd/m² at 14 V, luminous efficiency and power efficiency reach 6.24 cd/A and 2.45 lm/w.