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 10^3.8 and photocurrent switching of 500 ms.

通过液相剥落（LPE）制备的二维（2D）过渡金属二卤化二硫化碳（TMD）纳米片的喷墨印刷可实现简单，批量生产且低成本的光电设备。许多LPE工艺涉及有毒和对环境有害的溶剂。但是，分散剂限制了2D-TMD油墨的应用范围。在此，各种2D-TMD纳米片包括MoS ₂，MoSe ₂，WS ₂和WSe ₂除了几层石墨烯外，还使用基于两性离子分散剂的LPE工艺在水中进行喷墨印刷。具有阳离子和阴离子物种的两性离子是水溶性的，而与两个离子物种相关的烷基链部分普遍粘附在TMD纳米片的表面上，从而导致纳米片的高通量液体剥离。两性离子辅助的TMD纳米片在水中成功用作油墨，而无需使用添加剂来调节用于办公室喷墨打印机的油墨的粘度和表面张力。这会在可粘贴到人体皮肤上的各种基材（例如金属，氧化物和聚合物基材）上产生A4比例的大面积喷墨打印图像。与导电石墨烯纳米片油墨结合使用，可以开发出机械柔性，纸上的_2个通道的光电流开/关比约为10 ^3.8，光电流切换为500 ms。