Design of electron blocking layer with electron stabilizing unit for improved efficiency and lifetime in blue fluorescent organic light-emitting diodes

Abstract

Electron blocking materials for improved efficiency and lifetime in blue fluorescent organic light-emitting diodes were developed based on a molecular design to transport holes and withstand electron leakage. Two electron blocking materials, N,N-bis(4-(dibenzo[b,d]furan-4-yl)phenyl)-[1,1′-biphenyl]-4-amine (BPADBF) and N,N-bis(4-(dibenzo[b,d]furan-4-yl)phenyl)-9,9-dimethyl-9H-fluoren-2-amine (FADBF), were designed to have biphenylamine or fluorenylamine as the hole transport unit and phenyl substituted dibenzofuran as the electron stabilizing unit. They worked efficiently as the electron blocking materials of the deep blue fluorescent organic light-emitting diodes, increasing the external quantum efficiency from 6.1% to 7.2% and extending the lifetime by more than 50% up to 80% of the initial luminance.