Onset voltage shift in the organic thin-film transistor with an atomic-layer-deposited charge-injection interlayer

Abstract

Abstract High contact resistance at metal/organic interface is a general issue for organic thin-film transistors (OTFTs). We show that inserting an ultrathin vanadium oxide (VOx) interlayer by atomic layer deposition (ALD) at the metal/organic interface can greatly reduce the contact resistance and enhance the performance of pentacene OTFTs. When the ALD of VOx is performed at a relatively low temperature of 50 °C, the prepared transistor also exhibits a pronounced shift in onset voltage for several volts. The origin of this onset voltage shift is identified as the adsorption of dimethylamine, which is a byproduct of the ALD VOx process. We further show that the adsorption of dimethylamine can be well eliminated by elevating the ALD process temperature to 100 °C, which therefore offers a simple and straightforward approach to circumvent the issues with the onset voltage shift.