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

摘要

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 degrees 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 degrees C, which therefore offers a simple and straightforward approach to circumvent the issues with the onset voltage shift.