Green

red

blue and white organic light emitting diodes(OLEDs)were investigated.Remarkable improvement in stability has been demonstrated in doped green and red devices.The QA doped green OLED achieved a long life time of 14 000 hours at initial luminance of 100cd/m

2

.The red OLED doped with red dye DCJTB showed high stability

the half decay time reached 7 500 hours at the initial luminance of 50cd/m

2

.Three blue device were constructed as following:ITO/CuPc/NPB/TPBi/Alq/MgAg(Cell BT);ITO/CuPc/NPB/DPVBi:Perylene/Alg/Alq/MgAg(Cell BD);ITO/CuPc/NPB/JBEM:Perylene/Alq/MgAg(Cell BJ).Here TPBi is a hole blocking meterial

DPVBi is a blue host

and JBEM is a new blue emitting mate-rial.On basis of the blue devices

putting the red dopant DCJTB into blue material TPBi

DPVBi

JBEM

or green host Alq

four white devices were produced.Experimental shows that the blue cell and white cell with blocking layer TPBi had much shorter life time than that of the conventional cell.It is obvious that the blocking layer is not favorable to the stability of the device

it may be attributed to the high barrier between the hole transporting and blocking layers.For the blue devices with JBEM as the host or DPVBi as the host

the former has better stability than the latter

showing the life time of 1 035 hours at initial luminance of 100cd/m

2

.For the white OLEDs

just like the blue devices

the cell with JBEM as the host had better performance than that with DPVBI as the host

and the device with blue dye and red dye DCJTB in the same layer showed high stability

the half decay time reached 2846 hours at initial luminance of 100cd/m

2

.A green

white panel display with 96×60 pixels and resolution of 2 lines/mm are constructed.The driving circuit was designed to eliminate the cross-talk between the pixels

a good image was realized.