High luminance organic light-emitting diodes with efficient multi-walled carbon nanotube hole injectors

Abstract

We report on high luminance organic light-emitting diodes using acid functionalized multi-walled carbon nanotube (o-MWCNTs) as efficient hole injector electrodes, using a simple, solution processable device structure. At only 10 V, the luminance approaches 50,000 cd/m with an external quantum efficiency over 2% and a current efficiency greater than 21 cd/A. The investigation of hole-only devices shows that the mechanism for hole injection changes from injection limited to bulk limited because of the higher effective work function of the anode modified by the o-MWCNTs. We expect the enhancement of the local electric field, brought about by both the dielectric inhomogeneities within the o-MWCNT containing anode and the high aspect ratio carbon nanotubes, improves hole injection from the anode to the organic active layer at much lower applied voltage. © 2012 Elsevier Ltd. All rights reserved

Solution-processable graphene oxide as an efficient hole injection layer for high luminance organic light-emitting diodes

“…Recently, we have reported a luminance of nearly 50,000 cd m -2 with multi-walled carbon nanotube (MWCNTs) interlayer on ITO. 31 Compared with the 55 reported best results, high luminance of over 53,000 cd m -2 is obtained using our GO electrodes at a lower voltage, with most importantly a simple device fabrication process and without any device encapsulation or post processing. To our knowledge there are no reports with such high luminance 60 OLEDs using the material GO, with the result positioned to unlock a route of applying GO in flexible OLEDs and other electrode applications.…”

“…3 (b), the enhancement of current density for OLEDs with GO interlayers can be attributed to the improved effective WF and the creation of an interface energy step between ITO and 100 TPD, leading to a reduced energy barrier and improvement of hole injection efficiency with concomitant luminance increase. We have reported high luminance OLEDs with CNTs as the interlayer before, 31 but the effects of GO are very different 105 from that of CNTs. CNTs are 1-dimensional tubular carbon materials that scatter charge due to the topological variations from a planar 2D surface and don't form an uniform film on substrates.…”

Carbon for Sensing Devices

“…The Pd nanoparticle sensing elements were coated with MWCNTs by drop casting 50 µl of acid functionalized (o-MWCNTs) dispersed in distilled water (0.01 mg/mL)[186,187]. b The working mechanism of the CNT-Pd sensing element.…”

Hybrid metal grid-polymer-carbon nanotube electrodes for high luminance organic light emitting diodes

“…Some of the most promising candidates are poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) [7,8], silver nanowires (AgNW) [9], graphene [10,11] and carbon nanotubes (CNTs) [12]. Devices have been fabricated using these materials as the TCE [7,10,11] or as hole injection or extraction layers [13,14,15,16].…”