Overcoming contact issues in bottom-contact, short-channel organic transistors with van der Waals conformal contacts

Abstract

Miniaturization and high integration of organic field-effect transistors (OFETs) have long served as a pivotal driving force behind the advancement of organic electronics. Bottom-contact (BC) OFET device architecture offers an ideal platform for enabling high-density integration of organic devices. However, its performance exhibits significant degradation under short-channel conditions, primarily due to metal-semiconductor contact issues. Herein, we report a conformal contact transfer (CCT) strategy designed to address the contact-related issues in the BC OFETs, thereby sustaining high device performance under short-channel conditions. By functionalizing electrode surfaces and leveraging the compressive effect of interfacial water permeation, this approach significantly enhances van der Waals forces between organic semiconductor and metal electrodes while effectively eliminating trapped interfacial bubbles. This process ultimately yields a wrinkle-free, bubble-free, and conformal contact interface. Construction of this high-quality contact markedly improves carrier injection efficiency, which is accompanied by a reduction in the Schottky barrier height and a 6.5-fold decrease in contact resistance relative to traditional direct-contact configurations. The resulting BC OFETs with short-channel lengths demonstrate a high mobility of 9.43 cm²·V⁻¹·s⁻¹ with the largest channel-length-normalized mobility (μ/L) among previously reported devices based on identical material systems. This CCT strategy effectively addresses the performance degradation arising from interfacial contact constraints during OFET miniaturization, thus providing a novel pathway for advancing organic electronics toward higher integration density.