Conduction and transport in the ITO/AVB/AL light emitting diode

Abstract Current–voltage and impedance spectroscopy measurements have been carried out on the indium-tin-oxide (ITO)/1,4-bix-(9-anthylvinyl)-benzene (AVB)/Al light emitting diode. The impedance dependence of bias and frequency is discussed in term of the presence of a depletion layer in the bulk. Capacitance voltage measurements shows a linear behavior of C −2 with V which indicate the presence of a trap density less than ∼4×10 16  cm −3 . Current–voltage measurements indicate two mechanisms of conduction: a conduction limited by traps at lower forward bias and a SCL regime at higher forward voltages. In this device injection and conduction are dominated by holes. The hole mobility is determined using Mott–Gurney relation and was found to be on the order of 6.7×10 −5  cm 2 /Vs. The device is accurately modeled, in reverse and forward biases and for frequency lied between 10 kHz and 10 MHz, as a single parallel resistor and capacitor network placed in series with a resistance. Finally, we present a qualitative description of the electroluminescence mechanism of the device.