Selectively Metallized 2D Materials for Simple Logic Devices

We herein demonstrate, for the first time, transparent, flexible, and large-area monolithic MoS₂ transistors and logic gates. Each single transistor consists of only two components: a monolithic chemical vapor deposition-grown MoS₂ and an ion gel. Additional electrode materials are not required. The uniqueness of the device configuration is attributed to two factors. One is that a MoS₂ layer is a semiconductor, but it can be doped degenerately; monolithic MoS₂ can thus serve as both the electrodes and the channel of a transistor via selective doping of the material at certain positions. The other is the use of an electrolyte gate dielectric that permits effective gating (<3 V) even from an electrode coplanar with the channel. The resulting monolithic MoS₂ transistors yield excellent device performance, including a maximum mobility of 1.5 cm²/V s, an on-off ratio of 10⁵, and a turn-on voltage of -0.69 V. This unique transistor architecture was successfully applied to various semiconductors such as ReS₂ and indium-gallium-zinc oxide. Furthermore, the presented devices exhibit excellent mechanical, operational, and environmental stabilities. Fabrication of complex logic circuits (NOT, NAND, and NOR gates) by integration of the monolithic MoS₂ transistors is demonstrated. Finally, the monolithic MoS₂ transistor was connected to drive red, green, and blue light-emitting diode pixels, which yielded high luminance at a low voltage (<3 V). We believe that the unique architecture of the devices provides a facile way for low-cost, flexible, and high-performance two-dimensional electronics.