Influence of the hole injection layer on the luminescent performance of organic light-emitting diodes

✍ Scribed by Chen, Shih-Fang; Wang, Ching-Wu

• Book ID: 121077594
• Publisher: American Institute of Physics
• Year: 2004
• Tongue: English
• Weight: 431 KB
• Volume: 85
• Category: Article
• ISSN: 0003-6951
• DOI: 10.1063/1.1775282

✦ Synopsis

We investigate the influence of the hole injection layer (HIL) on the performance of vapor-deposited tris-(8-hydroxyquinoline) aluminum-based organic light-emitting diodes. Four different HIL materials were used: 4,4′, 4″-tris{N,(3-methylphenyl)-N-phenylamino}-triphenylamine) (m-MTDATA), 4,4′, 4″-tris{N,-(2-naphthyl)-N-phenylamino}-triphenylamine, copper phthalocyanine, and oxotitanium phthalocyanine. In all cases, Alq3 acts as the emitting layer as well as electron-transporting layers. Evidence showed that m-MTDATA exhibits a dense film structure and fine surface morphology, leading to easier hole migration at the indium tin oxide/m-MTDATA and m-MTDATA/hole-transport layer junctions. It also possesses a shallow bulk trap level, providing more detrapping holes from the bulk trap states to highest occupied molecular orbital states for transporting in m-MTDATA. We suggest that these are the main contributing factors to the superior current density–voltage and luminance-voltage performance of this device.