The dielectric constant of materials effect the property of the OLED

Several important materials have been used for the electron injection layer (EIL) of the organic light-emitting devices (OLEDs), such as LiF, NaCl, NaF, Al₂O₃, SiO₂, Si₃N₄, MgO, etc. LiF is the most usually used in OLED among these materials for its performance in OLED. The dielectric constant of LiF, NaCl, NaF is 9.036, 5.895 and 5.072, respectively, at 300 K [J. Fontanella, C. Andeen, D. Schuele, Phys. Rev. B 6 (1972) 582]. The thin film of these insulting layers here supply a very strong electric field to enhance the electrons injection and limit the holes injection to the emitting layer (EL). Then we kept the balance of the injected electrons and the holes, and then we got the excellent performing OLEDs.