Solution-processed ambipolar organic thin-film transistors and inverters in a single substrate through self-assembled monolayer-treated electrodes

Abstract

The demand for ambipolar organic thin-film transistors (OTFTs) is growing daily owing to their direct applications in single-component organic logic circuits, light-emitting transistors, and other types of integrated circuits. Donor–acceptor (DA) organic polymer semiconductors are the best option for developing the semiconducting channel layer in ambipolar OTFTs because they simplify the fabrication of various circuits with low power consumption and high noise margin. Because of its easy solution processability, well-controlled molecular structure, environmental stability, and operational stability, poly naphthalene diimide-thienylene-vinylene-thienylene (PNDI-TVT) is one of the best choices for the DA semiconducting layer of ambipolar OTFTs, which can then be used to develop organic integrated circuits on a single substrate. Due to a considerable mismatch between electron and hole mobility, little investigation has been done on the applications of PNDI-TVT-based ambipolar OTFTs in complementary organic integrated circuits. In this study, we developed high-performance ambipolar OTFTs using PNDI-TVT as a semiconductor and self-assembled monolayer (SAM)-treated gold as the source–drain electrodes, where the SAM treatment was used to achieve a balance between electron and hole mobilities, and thus to improve the performance of the complementary organic inverters fabricated in a single substrate using these ambipolar OTFTs. The SAM-based OTFTs exhibited the improved average electron and hole mobilities of 0.44 cm² V⁻¹ s⁻¹ (0.21 cm² V⁻¹ s⁻¹ without SAM) and 0.29 cm² V⁻¹ s⁻¹ (0.06 cm² V⁻¹ s⁻¹ without SAM), respectively, while the inverter showed a maximum voltage gain of ∼36 at 50 V which is ∼3 times higher than that without SAM treatment.