Effect of Carrier-Transporting Layer on Blue Phosphorescent Organic Light-Emitting Diodes

This study presented the effects of carrier-transporting layer (CTL) on electroluminescence (EL) performance a blue phosphorescent organic light-emitting diodes (PHOLEDs) with electron transporting host based three kinds electron-transporting layers (ETLs) including 3-(4-biphenyl-yl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (TAZ), diphenyl-bis[4-(pyridin-3-yl)phenyl]silane (DPPS) and 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB) two hole-transporting (HTLs) such as 4,4′-bis[N-1-naphthyl-N-phenyl-amino]biphenyl (NPB), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC). The carrier recombination exciton formation zones in PHOLEDs strongly depend mobility CTLs thickness, especially mobility. Between ETLs HTLs, high ETL results lower driving voltage than hole HTL did. In addition, thickness modulation is an effective approach to precisely control carriers restrict within EML avoid leakage emission CTL. For CTL pairs OLEDs using system, low also HTLs are key points confine charge for efficient photon emission. These findings show that appropriate good essential OLEDs.