Electrophosphorescent light-emitting diodes

for which both singlet and triplet excitons contribute to the light emission

have attracted great scientific and commercial attention because of their high quantum efficiency.Iridium-based complexes are the popular selection as the efficient dopant due to a relatively short phosphorescent lifetime.The electrophosphorescent polymers with iridium complex as a repeat unit incorporated into a conjugated main chain were investigated.In this case

the conjugated segments play the roles:a polymer ligand and a host for the energy transfer system.In this kind of phosphorescent polymers

the position and angle will affect the light wavelength and light efficiency of the PLEDbased on them.We demonstrated the efficient synthesis of the copolymers with Ir complexes incorporated onto fluorene-alt-carbazole backbone by Suzuki polycondensation via brominated iridium (Ⅲ) bis (1-phenylisoquinolyl-N

C2’) acetylactonate.With the different feed ratio from 0.1% to 0.5%

four polymers

named by PFCzIrPiq 01

PFCzIrPiq 02

PFCzIrPiq 03

and PFCzIrPiq05

were synthesized respectively.The resultant copolymers are easily soluble in common solvents such as toluene

tetrahydrofuran and chloroform

which provides for the facility in preparation of the polymer films by spin coating.The maximum external quantum efficiency of 2.8% and luminescent efficiency of 1.3 cd/Awere obtained from the device fabricated with copolymer PFCzIrPiq05.It indicates that the introducing complexes onto polymer backbone may be a better way to improve the efficiency of phosphorescent polymers in light-emitting diodes.