Effect of contact resistance on mobility determination by impedance spectroscopy

Abstract

The effect of contact resistance on the determination of charge carrier mobility in single-injection space-charge-limited (SCL) diodes is numerically examined. Contact resistance is inevitably involved in the equivalent circuit of the SCL diodes. It is found that the mobility is accurately determined when it is less than or equal to 1.0 × 10−5 cm2 V−1 s−1 even in the presence of contact resistance at a semiconducting layer thickness of 100 nm, which is comparable to the active layer thickness of organic electronic devices, such as organic light-emitting diodes and organic photovoltaic devices. In contrast, when the input mobility is greater than 1.0 × 10−4 cm2 V−1 s−1 for the numerical calculation, the calculated mobility decreases with increasing contact resistance. Such information is an important guideline for the accurate measurements of mobility in single-injection SCL diodes.