Inkjet-printed p-type tellurene and n-type MoS₂ transistors for CMOS electronics

Abstract Two-dimensional (2D) semiconductor materials combine exceptional electronic transport properties with mechanical flexibility and hence can be an ideal choice for large-area flexible and wearable electronics. While inkjet printing may be a suitable approach to fabricate high throughput electronic components on polymer substrates, solution-processed 2D semiconductor network transistors suffer from two major hindrances: extremely high inter-flake resistance and the lack of high-performance p-type semiconductors. This study shows that inkjet-printed tellurium nanowires or tellurene nanoflakes can offer high-performance p-type TFTs with current density up to 100 μA μm⁻¹ and an On–Off ratio >10⁵. In order to circumvent the high inter-flake junction resistance, a narrow-channel, near-vertical device architecture has been used that ensures predominantly intra-flake/ intra-nanowire transport, which resulted in three orders of magnitude increase in the current density compared to conventional devices without compromising on the On–Off ratio. Moreover, we show the whole device operation within ±2 V, with a threshold voltage close to 0 V. The complete device fabrication is carried out at room temperature, thereby making it compatible with inexpensive polymer substrates. Next, outstanding device performance has also been realized with electrochemically-exfoliated and inkjet-printed n-type MoS₂ TFTs, demonstrating a current density of 60 μA μm⁻¹ and an On–Off ratio of 10⁶. Furthermore, we show tellurene-based p-type depletion-load unipolar inverters and CMOS inverters alongside n-type MoS₂ TFTs, demonstrating a signal gain of 12 and 11, respectively. The CMOS inverters are found to operate at a frequency of 1 kHz.