Organic light-emitting diodes with carbon nanotube cathode-organic interface layer

Improved performance of organic light-emitting diodes (OLEDs) was achieved by implementing a carbon nanotube (CNT) layer at the cathode-organic interface, spin coated between the organic layer and the cathode. The small geometry of CNTs could enable the enhancement of the electric field around them, thus increasing electron injection efficiency from the cathode to the organic layer. In addition, as measured from the x-ray absorption and emission spectroscopy, incorporation of CNT could reduce the lowest unoccupied molecular orbital of the organic material at the cathode-organic interface, thus effectively decreasing the barrier for electron injection. Increased electron injection and luminance characteristics were demonstrated for both polymer and small molecule based OLED devices.