A Study on Highly Efficient Organic Electroluminescent Devices

In order to improve the device performances of organic electroluminescent devices (OELDs), the efficiency of carrier injections into the organic layers from electrodes and the balance of injected carrier densities in the emission region are critical factors. Especially, energy barriers, which exist at the interfaces between electrodes and organic layers, interrupt carrier injections, which lead to unbalanced carrier densities. In this study α-septithiophene (α-7T), as a buffer layer, and composite cathode composed of Al and CsF were formed to improve hole and electron injections, respectively. The orientations of α-7T molecules were adjusted using the simple rubbing method and the mass ratio of CsF was varied from 1 to 10 wt