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The challenge of achieving Ohmic contacts fundamentally limits the performance of organic electronic devices, primarily due to high contact resistance resulting from Schottky contact at the metal–organic semiconductor contact interface. This study demonstrates a general strategy to significantly diminish contact resistance in copolymer organic field-effect transistors (OFETs) by achieving a quasi-Ohmic contact where the dominant mechanism is tunneling injection rather than thermionic emission. By introducing a solution-processed dopant-assisted modification (DAM) layer fabricated via simple orthogonal solvent processing at the interface, a heavily doped interfacial region is created. This region dramatically narrows the Schottky barrier width, enabling efficient charge injection via the tunneling injection enhancement effect. An optimized DAM layer achieves an ultralow contact resistance of 66 Ω cm, representing an 85% reduction vs the conventional device. Concurrently, the field-effect mobility increases by 273% to 1.68 cm2 V−1 s−1, while the threshold voltage decreases by 36% to −9.37 V. The DAM layer exhibits broad applicability and good stability, while also showing potential for flexible OFETs. This study provides a simple and universal interfacial engineering pathway to high-performance organic transistors, paving the way for advanced organic integrated circuits.
Chang et al. (Mon,) studied this question.