Enhanced hole injection in a bilayer vacuum-deposited organic light-emitting device using a p-type doped silicon anode

We report the fabrication of a vacuum-deposited light-emitting device which emits light from its top surface through an Al cathode using p-type doped silicon as the anode material. Enhanced hole injection is clearly demonstra ted from the p-Si anode as compared to the indium-tin-oxide (ITO) anode. Th e mechanisms of hole injection from both the p-Si and ITO anodes into the o rganic layer are investigated and a possible model based on anode surface b and bending is proposed. During the operation of the organic light-emitting device, the surface band bending of the anode plays a very important role in modifying the interfacial barrier height between the anode and the organ ic layer. (C) 1999 American Institute of Physics. [S0003-6951(99)01604-6].