Organic electroluminescence(OEL) devices have attracted considerable interest due to their potential application in flat panel displays.The color of EL devices is readily tuned by the proper choice of dopant dispersed in a host.Incomplete energy transfer can then result in light emission from both the host and the dopant

this way has been used to obtain white light from organic small-molecule-based devices. In this paper

luminescence of blue emitting material DPVBi doped with red dye DCJTB were investigated.Based upon the photoluminescence results of DPVBi doped by DCJTB with different mass concentration

the organic light emitting diodes(OLEDs) were fabricated with the electroluminescent layer consisting of DPVBi doped by different mass concentration DCJTB. In the device structure of ITO/CuPc/NPB/DPVBi:DCJTB/Alq

3

/LiF/Al

doping mass concentration of DCJTB contain 0%

0.03%

0.08% and 0.25%.It was observed that the blue bands gradually decrease with the increase of the doped DCJTB mass concentration.This indicates that energy transfer does occur from DPVBi to DCJTB.When the mass concentration of DCJTB is 0.08%

white light emission can be obtained.As the DCJTB mass concentration is further increased

the spectrum deviate from the white colour because of more energy transfered from DPVBi to DCJTB.It is expected that the CIE coordinates of the white colour could be further optimized by adjusting the dopant concentration.The results demonstrate that white emission can be realized through the incomplete energy transfer of blue emitting material DPVBi to red dye DCJTB in the same emitting layer.The white device shows the increase in relative intensity of blue to red emission with increasing applied voltage.For the white device with CIE coordinates

x

=0.25

y

=0.32

the maxiumum luminance

luminance and the maximum luminous efficiency under current density of 20mA/cm

2

are 7 822

489cd/m

2

and 1.75 lm/W

respectively.