Three types of blue-violet light-emitting devices based on an excito n- confined structure have been prepared, in which different materials were used as emitting layers and hole-transporting layers. They had structures of ITO/CuPc/ NPB/CPB/TPBi/Alq 3/LiF/Al(D NC), ITO/CuPc/J03/CBP/TPBi/Alq 3/LiF/Al(D JC) and ITO /CuPc/J03/FNPD/TPBi/Alq 3/LiF/Al(D JF). Here copper phthaloc yan ine (CuPc) acted as hole-injecting layer(HIL), N,N-bis-(1-naphthyl)-N,N-di phenyl-1.1bipheny1-4-4-diamine(NPB) and J03 hole-transporting layers (HTLs) , 4,4'-dicarbazolyl-1,1'-biphenyl (CBP) and FNPD as emitting layers(EMLs), N, arylbenzimidazoles (TPBi) as hole-blocking layer(HBL), and tris(8-quinolinolat o) aluminium complex(Alq 3) as electron-transporting layer(ETL). TPBi applied her e is a good confinement to both charges and excitons, which make the devices emit blue-violet light or iginating from the emitter, CBP and FNPD. Their characteristics have also been i nvestigated. The result shows that the device D NC based on NPB/CBP has the best performance among the three devices. The excellence of D NC is attrib uted to the better hole-transporting ability of NPB as compared with J03, and t he better emitting ability of CBP as compared with FNPD, although the best match ing of energy levels is found in the hole-transporting layer and emitting layer of the device D JF.
