A novel p-dopant with low diffusion tendency and its application to organic light-emitting diodes

The novel p-dopant 2,3-di(N-phthalimido)-5,6-dicyano-1,4-benzoquinone (BAPD) was synthesized and compared to the state-of-the-art dopant F4TCNQ. BAPD shows a higher evaporation temperature and thermal stability than F4TCNQ, presumably due to its higher molecular weight and bulkiness. The efficiency of the host-to-dopant electron transfer as well as the diffusion characteristics of the p-dopants were investigated by ultraviolet photo emission spectroscopy (UPS) and X-ray photo emission spectroscopy (XPS). Although BAPD is a less strong p-dopant than F4TCNQ, the lower diffusion tendency and higher thermal stability of this new class of dopants forms an attractive potential for the lifetime improvement of organic electronic devices.