Efficient quantum dot light-emitting diodes with solution-processable molybdenum oxide as the anode buffer layer

Quantum dot light-emitting diodes (QD-LEDs) are characterized by pure and saturated emission colors with narrow bandwidth. Optimization of the device interface is an effective way to achieve stable and high-performance QD-LEDs. Here we utilized solution-processed molybdenum oxide (MoOx) as the anode buffer layer on ITO to build efficient QD-LEDs. Using MoOx as the anode buffer layer provides the QD-LED with good Ohmic contact and a small charge transfer resistance. The device luminance is nearly independent of the thickness of the MoOx anode buffer layer. The QD-LEDs with a MoOx anode buffer layer exhibit a maximum luminance and luminous efficiency of 5230 cd m(-2) and 0.67 cd A(-1) for the yellow emission at 580 nm, and 7842 cd m(-2) and 1.49 cd A(-1) for the red emission at 610 nm, respectively.

Dispersive hole transport in polymer:carbon nanotube composites

The hole transport properties of poly(2-methoxy, 5-(2'-ethyl-hexoxy)-p-phenylene vinylene) (MEH-PPV) blended with acid oxidized multiwall carbon nanotubes (COOH-MWCNTs) were investigated in a diode configuration using the time-of-flight (TOF) photocurrent method. While the room temperature hole mobility in pure MEH-PPV films was non-dispersive with positive field dependent mobility, MEH-PPV:COOH-MWCNT blended devices exhibited dispersive transport and negative field dependent mobility. This indicates that the hole mobility in this composite is influenced by positional disorder caused by the presence of COOH-MWCNTs in the MEH-PPV matrix. These results strongly suggest that the distribution of COOH-MWCNTs optimising in the organic matrix is important for charge transport in the high mobility nanotube component to be activated, when used in hybrid material systems.