Inkjet printing of two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets fabricated by liquid-phase exfoliation (LPE) allows simple, mass-producible, and low-cost photo-electronic devices. Many LPE processes involve toxic and environmentally hazardous solvents; however, dispersants have restricted the extent of applications of 2D-TMD inks. Herein, various 2D-TMD nanosheets, including MoS2, MoSe2, WS2, and WSe2, in addition to few-layered graphene, are inkjet-printed using a LPE process based on zwitterionic dispersants in water. Zwitterions with cationic and anionic species are water-soluble, while alkyl chain moieties associated with two ionic species adhere universally on the surface of TMD nanosheets, resulting in high throughput liquid exfoliation of the nanosheets. The zwitterion-assisted TMD nanosheets in water are successfully employed as an ink without the need for additives to adjust the viscosity and surface tension of the ink for use in an office inkjet printer; this gives rise to A4 scale, large-area inkjet-printed images on diverse substrates, such as metals, oxides, and polymer substrates patchable onto human skin. Combination with conductive graphene nanosheet inks allowed the development of mechanically flexible, biocompatible-printed arrays of photodetectors with pixelated MoSe2 channels on a paper exhibiting a photocurrent ON/OFF ratio of approximately 103.8 and photocurrent switching of 500 ms. [Figure not available: see fulltext.].
Bibliographical noteFunding Information:
This research was supported by the Creative Materials Discovery Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (2018M3D1A1058536). This research was also supported by a grant from the NRF funded by the Korean government (MEST) (Nos. 2017R1A2A1A05001160 and 2016M3A7B4910530). This work is based upon work supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under Industrial Technology Innovation Program (No.10063274).
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Electrical and Electronic Engineering