Effect of type-II quantum well of m-MTDATA/alpha-NPD on the performance of green organic light-emitting diodes

The type-II multiple quantum well (MQW) structure is prepared and introduced into green organic green light-emitting diodes consisting of 4,40-bis-[N-(naphthyl)-N-phenyl-amino]biphenyl (a-NPD) and tris-(8-hydroxyquinolinato)-aluminum (Alq3). The quantum well (QW) and wall are fabricated by 4,40 ,400-tris-(3-methylphenylphenylamino)triphenylamine (m-MTDATA) and a-NPD, respectively. The device performance of MQW organic light-emitting diodes (OLEDs) has been improved; the luminous efficiency by 25% and power efficiency by 17% compared with the reference device. The performance improvement can be explained by the increased electron–hole balance in the device due to the hole confinement in the QW structure. & 2008 Elsevier Ltd. All rights reserved.