OLED materials, first in 1936, were made by Destrian to disperse organic fluorescent compound materials in polymers to make films, and found the earliest OLED materials. In 1963, the research team of Pope et al. of New York University in the United States observed blue electroluminescence when a high voltage of 400 volts was applied to a 20-millimeter tantalum single crystal. This new discovery opens up the research atmosphere of OLED materials. What triggered the enthusiasm for OLED research was in 1987, published by C.W. Tang and Van Slyke et al. of Kodak Company, USA, on the paper of Small Molecular OLED (SMOLED or OLED) with double-layer structure. Their research adopted a high vacuum thermal evaporation method and used a low-work-function magnesium-silver alloy at the cathode part to improve the electron injection efficiency, and to produce a highly efficient green OLED luminescent material assembly. Its contribution is that as long as the low driving voltage is about 10 volts, 1% external quantum efficiency can be achieved, the luminous efficiency is about 1.5 lm/W, and the brightness can be as high as 1000 cd/m2. This led to the researcher’s upsurge of research into the luminescence of OLED materials.