Polyquinoxaline as an electron injecting material for electroluminescent device

A series of 2,3-disubstituted poly(quinoxaline-5,8-diyl) (PQx) was clarified to be an excellent electron injecting material for electroluminescent (EL) devices, since these have many advantageous properties such as high electron affinity (Ea:3.3 ~ 3.4 eV), good thermal stability, good processability and sufficiently low refractive index. On the other hand, since poly(p-phenylenevinylene) (PPV) was known as a good hole injecting material (ionization potential, Ip:5.1eV), an EL device with ITO/PPV/PQx/Metal type structure was suggested. It was shown that the quantum efficiency of the cell was about twice as high as that of ITO/PPV/Metal cell. Related physical and optical properties of PQx derivatives are also investigated.