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Proceedings Paper

Controlling interfacial phenomena to enhance performance in organic field-effect transistors (Conference Presentation)

Paper Abstract

Organic thin-film transistors (OTFTs) are a key technology for enabling novel electronics such as flexible displays, low-cost sensors, or printed RFID tags. Device mobility is the primary figure of merit for OTFTs, but a low contact resistance is critical to achieving marketable performance. The energy level mismatch at the electrode/semiconductor interface hinders charge injection, limiting device performance. This issue has been addressed through chemical treatments with self-assembled monolayers, insertion of metal oxide interlayers, and doping. Here we combine these treatments with modified electrode deposition and post-deposition processing and evaluate the impact on the device properties. Specifically, we alter the contact deposition rate and flame anneal the electrode surface in bottom contact/top gate OTFTs based on the polymer semiconductor indacenodithiophene-co-benzothiadiazole (C16IDT-BT). Tuning the deposition rate leads to larger, flatter grains of gold, increasing the degree of order within the SAM at its surface and creating high work function channels that enhance charge injection. We achieved contact resistances of 200 Ωcm, boosting device mobility up to 10 cm2V-1s-1, a factor of three improvement over previous C16IDT-BT devices in this geometry with the same gate dielectric. We found that flame annealing is effective for further optimizing the gold contact surfaces, increasing grain size by an order of magnitude over those in as-deposited films. Here, a butane torch was passed directly over the contacts and substrate for a short period of time (5 minutes). We determined the impact on device characteristics, including mobility, on/off ratio, subthreshold swing, and threshold voltage.

Paper Details

Date Published: 10 September 2019
Proc. SPIE 11097, Organic and Hybrid Field-Effect Transistors XVIII, 110970F (10 September 2019); doi: 10.1117/12.2529544
Show Author Affiliations
Matthew Waldrip, Wake Forest Univ. (United States)
Zachary A. Lamport, Wake Forest Univ. (United States)
Iain McCulloch, King Abdullah University of Science and Technology (Saudi Arabia)
Imperial College London (United Kingdom)
Oana D. Jurchescu, Wake Forest Univ. (United States)

Published in SPIE Proceedings Vol. 11097:
Organic and Hybrid Field-Effect Transistors XVIII
Iain McCulloch; Oana D. Jurchescu, Editor(s)

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