Charge-carrier induced barrier-height reduction at organic heterojunction

In order to provide an accurate theoretical description of current density–voltage (J-V) characteristics of an organic heterojunction device over a wide range of electric fields at various temperatures, it is proposed that an accumulation of charge carrier at the heterojunction will lead to a reduction in the barrier height across the heterojunction. Two well-known hole-transporting materials, 4,4^′,4^″-Tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine (MTDATA) and N,N^′-diphenyl-N,N^′-bis(1-naphthyl)(1,1^′-biphenyl)-4,4^′ diamine (NPB), were used to fabricate unipolar heterojunction devices. It is found that the J-V characteristics depend strongly on applied bias. The simulated J-V characteristics of the heterojunction device, with the modified injection model, are found to be in excellent agreement with the experimental data.