Highly efficient near-infrared emission from binuclear cyclo-metalated platinum complexes bridged with 5-(4-octyloxyphenyl)-1,3,4-oxadiazole-2-thiol in PLEDs

A novel near-infrared-emitting binuclear platinum complex of (piq)(2)Pt-2(mu-C8OXT)(2) was synthesized and characterized, in which piq is 1-phenylisoquinolinato and C8OXT is a bridging ancillary ligand of 5-(4-octyloxyphenyl)-1,3,4-oxadiazole)-2-thiol. Its optophysical, electrochemical and electroluminescent characteristics were primary studied. This binuclear platinum complex exhibited an intense UV absorption at about 493 nm from the metal-metal-to-ligand charge transfer transition and a bright near-infrared emission at 721 nm in chloromethane. Using (piq)(2)Pt-2(mu-C8OXT)(2) as a single dopant, its single-emissive- layer polymer light- emitting devices presented a high-efficiency near-infrared emission peaked at 702 nm with the maximum external quantum efficiency of 6.3% at 7.6 mA cm(2). This work provides an efficient approach to realize high-efficiency near-infrared emission by binuclear platinum complexes. (C) 2012 Elsevier B.V. All rights reserved.