A Critical Outlook for the Pursuit of Lower Contact Resistance in Organic Transistors. Issue 2 (7th October 2021)

• Record Type: Journal Article
• Authors: Borchert, James W.; Weitz, R. Thomas; Ludwigs, Sabine; Klauk, Hagen
• Is Part Of: Advanced materials. Volume 34:Issue 2(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-07
• Subjects: charge injection -- contact resistance -- Fermi‐level pinning -- interfaces -- organic transistors; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202104075
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: To take full advantage of recent and anticipated improvements in the performance of organic semiconductors employed in organic transistors, the high contact resistance arising at the interfaces between the organic semiconductor and the source and drain contacts must be reduced significantly. To date, only a small portion of the accumulated research on organic thin‐film transistors (TFTs) has reported channel‐width‐normalized contact resistances below 100 Ωcm, well above what is regularly demonstrated in transistors based on inorganic semiconductors. A closer look at these cases and the relevant literature strongly suggests that the most significant factor leading to the lowest contact resistances in organic TFTs so far has been the control of the thin‐film morphology of the organic semiconductor. By contrast, approaches aimed at increasing the charge‐carrier density and/or reducing the intrinsic Schottky barrier height have so far played a relatively minor role in achieving the lowest contact resistances. Herein, the possible explanations for these observations are explored, including the prevalence of Fermi‐level pinning and the difficulties in forming optimized interfaces with organic semiconductors. An overview of the research on these topics is provided, and potential device‐engineering solutions are discussed based on recent advancements in the theoretical and experimental work on both organic and inorganic semiconductors. Abstract : Though organic transistors have long been considered as a potential cornerstone technology for flexible electronics applications, their widespread commercialization in high‐frequency circuits has been substantially impeded by high contact resistance. A review of the state‐of‐the‐art reveals the pivotal role of the organic‐semiconductor morphology and the key challenges now to be overcome, such as Fermi‐level pinning and low charge‐carrier densities.