White organic light-emitting diodes based on emission from DPVBi-doped 4,48-bis (2,28-diphenylvinyl)-1,18-biphenyl

摘要

White organic light-emitting diodes were fabricated by using 4,48-bis （2,28-diphenylvinyl）-1,18-biphenyl （DPVBi） as a dopant with a structure of ITO/4,4′-bis[N-（1-naphthyl-1-）-N-phenyl-amino]-biphenyl （NPB,50 nm）/NPB:DPVBi （molecular weight ratio 10∶1,30 nm）/tris-（8-hydroxyquinoline）aluminum（Alq3,20 nm）/LiF（1 nm）/Al.A broad emissive band with four major peaks of 438,464,496 and 520 nm was obtained by electroluminescence spectra,of which 438 nm-,464 nm-and 520 nm-peak come from emission of NPB,DPVBi and Alq3,respectively,and 496 nm-one resulted from the emissive superposition of three materials above.The emission from DPVBi was attributed to the charge trapping from NPB.The emission region was transferred partly from Alq3 to DPVBi-doped NPB by introducing the dopant DPVBi,which leads to emission of DPVBi and an enhanced emission from NPB.The maximum luminance and current efficiency were 4721 cd/m2 at 22 V and 0.80 cd/A at 5V,respectively.