Enhancement of Organic Light-Emitting Diodes Efficiency Using Carbon Nanotube Doped Hole-Injection Layer on the Al-Doped ZnO Anode

Nanocomposite layers consisting of multi-walled carbon nanotubes (MWCNTs)-doped poly(3-hexylthiophene) (P3HT) were employed as a hole-injection layer (HIL) in organic light-emitting diodes (OLEDs). The structure of OLED is glass/Al-doped zinc oxide/MWCNTs-doped P3HT/N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl) benzidine/ tris(8-hydroxyquinolinato) aluminum/LiF/Al. The obtained current efficiency of the OLED is as high as ∼10 cd/A, which is about 30% higher than that of a conventional device without a MWCNTs-doped HIL. As a result, the MWCNTs-doped HIL could elevate the overall performance of the OLEDs and can be easily adopted in the manufacturing process.