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.
Keywords: MoS; doping; flexible; monolithic; transistor.