Performance Enhanced OLEDs Using a Li3N Doped Tris(8-Hydroxyquinoline) Aluminum(Alq3) Thin Film as Electron-Injecting and Transporting Layer

Lithium nitride (Li3N) is demonstrated to be an efficient n-type dopant in the widely used electron-injecting and transporting material tris(8-hydroxyquinoline) aluminum (Alq3) for Organic Light-emitting Diodes (OLEDs). Li3N doped Alq3 thin film can availably enhance the electron injection and transport ability of OLEDs, which can improve the luminance and the efficiency of doped OLEDs compared to the referenced device. Device ITO/m-MTDATA/NPB/Alq3/Alq3:Li3N/Al with optimized doping concentration and thickness exhibits a maximal luminance of 28640 cd/m2, and current efficiency 2.30cd/A, a turn-on voltage 2.9V, in contrast to 6334 cd/m2, 0.44cd/A and 4.7V for the non-doped device. Processing of Li3N is much easier and safer than that of alkaline metals, since Li3N is air-stable and has low deposition temperature which is similar to that of organic semiconductor materials.