Organic field-effect transistors (OFETs) are core components in flexible electronics, holding great promise for applications in flexible displays, wearable devices, smart sensors, and electronic skins. However, in practical operation, conventional OFETs suffer from substantial defects at the heterogeneous organic semiconductor (OSC)/dielectric interface, which severely compromise device operational stability
To address this issue, a research team at Tianjin University has proposed a "covalent bridging" strategy for engineering the OSC/dielectric interface at the molecular level. In this design, the dielectric functionality is intrinsically integrated into alkylated organic semiconductor molecules. The insulating alkyl side chains of the alkylated OSC are ingeniously exploited to serve simultaneously as both an integral part of the semiconducting molecular structure and the dielectric layer, thereby effectively reducing defects at the OSC/dielectric heterointerface. The team validated this concept using alkylated DNTT derivatives as a model system. Experimental results demonstrate that the insulating alkyl chains effectively suppress leakage currents while preserving excellent charge-transport capability. Moreover, the alkyl chains substantially reduce the dielectric thickness, enabling low-voltage device operation. Combined theoretical calculations, device characterizations, and simulations further confirm that this molecular-scale interface engineering significantly lowers the interface trap-state density and enhances both interfacial quality and device stability.
Organic transistors based on the C 10 ‑DNTT fabricated with this strategy exhibit outstanding performance. The devices operate at voltages as low as –1 V and retain over 96% of their initial current after 10,000 s of continuous bias stress. The researchers further constructed organic logic circuits using these transistors; the resulting inverters achieve a voltage gain of 127.6 and a noise margin of 95.3% at a supply voltage of 2.5 V, with a signal delay time of only 50 µs. After 50 consecutive switching cycles, the circuit performance shows no significant degradation, demonstrating excellent operational stability.
This work offers a new molecular‐level design paradigm for resolving interfacial defect issues in organic electronic devices, overcoming the long‐standing trade‐off between low‐voltage operation and high operational stability. Looking ahead, this strategy holds promise for applications in wearable health‐monitoring systems, electronic skins, smart sensors, and next‐generation low‐power organic integrated circuits, providing a robust foundation for the continued advancement of flexible electronics.
Science Bulletin
Experimental study