Hole blocking in carbon nanotube–polymer composite organic light-emitting diodes based on poly (m-phenylene vinylene-co-2, 5-dioctoxy-p-phenylene vinylene)

Abstract

In order to investigate the role of carbon nanotubes in a polymer matrix, organic light-emitting diodes were fabricated from a polymer composite composed of poly (m-phenylene vinylene-co-2,5-dioctoxy-p-phenylene) (PmPV) and dispersed single-wall carbon nanotubes (SWNTs). Tris-(8-hydroxyquinolinolato) aluminum (Alq3) doped by Nile Red was used as an emissive material between the polymer composite and cathode. The device fabricated without SWNTs dispersed in the PmPV shows a dominant emission near red at 600 nm, which is in the range of the characteristic emission of Nile Red-doped Alq3, with a small amount of green emission from the PmPV. However, the devices fabricated with the polymer composite show an increase in the oscillator strength of the green emission with a dominant emission peak near 500 nm, the characteristic emission of PmPV. This was observed for SWNT concentrations up to 0.1 wt %. The shift in the emission indicates that the SWNTs in the PmPV matrix act as a hole-blocking material that results in a shifting of the recombination region from the Nile Red-doped Alq3 layer to the PmPV composite layer.

Multicolor Luminescence from Semiconductor Nanocrystal Composites Tunable in an Electric Field

“…Therefore, the mechanism for the formation of the excited state in the polymer involves the ruthenium complex in a stepwise electron transfer process. In the case of the PDPV-ZnO:Mg composite the band gap of ZnO is higher than that of the polymer and the latter mechanism of the electric-field switching between blue-green and red emissions does not work (as well as the mechanism proposed for the emission from PPV-carbon nanotube composite ( Woo et al, 2000). Fig.…”

Carbon Nanotubes and Semiconducting Polymer Nanocomposites

“…The buffer layer leads to a reduction of the charge injection barrier and an even charge distribution with a large contact area at the electrodes/organics interface. A recent work shows that the dispersion of SWNTs in a host polymer (PmPV, hole conducting) traps the holes in a double emitting organic light emitting diode (DE-OLED) [63]. The device fabricated without SWNTs dispersed in the PmPV has shown a dominant emission near red at 600 nm, which is in the range of the characteristic emission of Nile Red-doped Alq3, while the addition of a www.intechopen.com small amount of SWNTs enhances a green emission, In addition, the devices fabricated with the polymer/SWNTs composite have shown an increase in the oscillator strength of the green emission with a dominant emission peak near 500 nm, the characteristic emission of PmPV.…”

“…For biosensor applications, it has been demonstrated that the CPs/CNTs nanocomposites are very attractive as tranducers because they provide the best electron transfer and assure a faster www.intechopen.com ion mass transfer [28]. In some host polymers, the CNTs additive has found to act as a holeblocking causing a shift of the recombination emission [29,63]. The interaction between host polymer and CNTs additive is considered to be the main reason accounting for all of these modifications.…”

A study on the effect of surface treatment of carbon nanotubes for liquid crystalline epoxide–carbon nanotube composites

“…The excellent electrical properties of CNs make them attractive candidates for new electronic devices. [8][9][10] Research [11][12][13][14][15] into the mechanical properties of CN composites has revealed that CNs can be potentially used as reinforcement fillers in polymer composite systems.…”

“…As hard conductive materials, LCE-CN composites show great potential for use as antistatic coatings or for electromagnetic shielding for electronic devices. [20][21][22][23] CNs offer an alternative for polymer matrix reinforcement [20][21][22] and enhance the electronic properties [8][9][10] of the resulting composite. Although many studies have sought to improve the mechanical performance of polymer-CN composites, they provide only limited information concerning the surface modification of CNs.…”