Current limiting mechanisms in indium-tin-oxide'poly3-hexylthiophene' aluminum thin film devices

We studied the temperature dependent current-voltage characteristics of regioregular poly (3-hexylthiophene 2.5-diyl) (P3HT) thin films sandwiched between indium tin oxide (ITO) and aluminum (Al) electrodes (ITO/P3HT/Al devices), with the aim of determining the current limiting mechanism(s) in these devices, and the temperature and/or applied electric field range(s) in which these mechanisms are valid. The current-voltage characteristics of the ITO/P3HT/Al devices showed that current flow across the device is limited by hole injection at the Al/P3HT interfaces at temperatures below 240 K, when the device is biased with high potential on Al. Above this temperature, the bulk transport properties control the characteristics. For the reverse bias, the ITO/P3HT contact does not limit the current; instead it is controlled by a space charge that accumulates due to the low charge carrier mobility in the polymer. An expression that provides a criterion to determine the validity of applying either the Richardson–Sc...

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