Synthesis, optoelectronic properties of a dinuclear platinum(II) complex containing a binary cyclometalated ligand in the single-emissive-layer PLEDs.

A novel dinuclear platinum complex of (dfppy-mhb-dfppy)Pt(2)(acac)(2) was synthesized and characterized, where dfppy-mhb-dfppy is a binary C^N cyclometalated ligand containing two bridged 2,4-difluorophenylpyridine (dfppy) units and acac is 2,4-pentanedione anion. Compared to previously reported dinuclear platinum complexes with a binary ancillary ligand, this dinuclear platinum complex showed more intense excimer emission, peaking at 617 nm, besides its intrinsic emission in dilute dichloromethane solution. Single-emissive-layer (SEL) polymer light-emitting devices (PLEDs) using (dfppy-mhb-dfppy)Pt(2)(acac)(2) as dopant and a blend of poly (N-vinylcarbazole) (PVK) and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) as host matrix exhibited stable white emission at 1 wt% doping concentration under applied voltages from 7 V to 11 V. The stable white emission observed in the (dfppy-mhb-dfppy)Pt(2)(acac)(2)-doped SEL PLEDs indeed implies that the dinuclear platinum complex constructed by a binary cyclometalated ligand has a potential application in white-emitting SEL PLEDs.