An analytical model to calculate the electroluminescence(EL) profile at high electric field in single layer structure

taking into account the charge injection process at each electrode

fission and recombination of polaron-excitons in disordered system

is presented.The influences of the barriers of metal/organic interface on EL efficiency are thoroughly studied.When the barrier exceeds about 0.3eV

the EL efficiency will become very small.While lowering the barrier of metal/organic interface

the EL efficiency will be enhanced.With increasing applied voltages

the injection efficiency increases while the recombination efficiency decreases

and when the electric field increases to a critical value

the EL efficiency reaches the maximum and then decreases.It indicates that the EL efficiency is dominated by injection at lower voltages and recombination at higher voltages.It is found this model can reasonably eluci-dates the influence of injection and recombination processes on EL efficiency

which provides a theory to improve the EL efficiency

to optimize the structure and to select suitable electroluminescent materials.