Highly enhanced electron injection in organic light-emitting diodes with an n-type semiconducting MnO2 layer

► Highly enhance electron injection with an n-type semiconducting MnO2 EIL. ► Electronic structures with in situ photoelectron spectroscopy. ► Reduction of the electron injection barrier without Alq3 destruction. ► Efficient electron injection is observed with Ag cathode or inverted devices.