Organic light-emitting diodes(OLEDs) are of great interest

since they efficiently emit light in the visible region and give promising applications.Full color displays require pure red

green and blue emission.However

the broad nature of the luminescent spectra of these organic molecules leads to the poor luminescent purity

which is dull and

thus

not suited for actual display applications.Rare earth complexes are very suitable for full color displays because of their sharp emission bands.In addition

EL efficiency based on rare earth complex is not limited by spin ruling

since their photoluminescence results from the formation of both singlets and triplets of the ligands

and then transferring energy to lanthanide cores.Theoretically

the upper limit of inner quantum efficiency can reach 100%

which is four times higher than that of the devices using other fluorescent material.For OLEDs

the development of high-perfor-(mance) red emission is still much in demand compared with both green and blue emission.A new organic complex of rare-earth europium(Eu) EuL

1

L

2

was reported.The electroluminescence and photoluminescence of this Eu complex were studied.The multilayer devices with the structure of ITO/PVK:PBD:EuL

1

L

2

/PBD/Alq

3

/Mg:Ag/Ag were fabricated

using PVK:PBD:EuL

1

L

2

as emitting layer

PBD as(exciton) block layer

and Alq

3

as electron transporting layer.The emission from electron transfer layer was easily seen because the lifetime of exicton of Eu complex.In the experiment

a electron transfer material PBD was used as exciton block layer.Alq

3

emission intensity become weaker than that of Eu complex

with the increase of the exciton block layer PBD thickness.As the block layer 80 nm

a pure red light with a peak of 612 nm and a half bandwidth of 10 nm

attribute to the(emission) of trivalent europium

was observed clearly.The assignment of the emission bands is referenced to(analogous) complex: 576 nm(

5

D

0

→

7

F

0

)

590 nm(

5

D

0

→

7

F

1

)

612 nm(

5

D

0

→

7

F

2

)

652 nm(

5

D

0

→

7

F

3

)

700 nm(

5

D

0

→

7

F

4

).The CIE coordinates of resulting emission was(0.608

0.339)

a maximum luminescence brightness of 20cd/m

2

and external quantum efficiency brightness of 0.09% were achieved.