Liquids are often considered an aggressive medium for standard electronics due to strong polarization effects and electrolysis [1]. However, they can turn advantageous, for example, to operate thin-film transistors (TFT) in the so-called solution-gated architecture [1-4]. In such devices, a drop of water, saline solution, or ionic liquid replaces the dielectric layer of regular TFTs, and an immersed gate electrode controls the device channel via the electrostatic coupling between ions and the semiconductor charge carriers [1–4]. In this talk, we will present the basics of solution-gated transistors, viz. types of device architecture, how to fabricate and operate them. We will discuss how such device platform can be used to electrically characterize thin films made of molecular/organic semiconductors and 2D materials (viz. liquid-phase exfoliated MoS2).
Finally, we will show how such devices can be used as powerful electrical transducers to develop chemical sensors and biosensors.

[1] T. Cramer, et al., J. Mater. Chem. B. 1, p. 3728–3741 (2013).
[2] R.F. de Oliveira, et al., Org. Electron. 31, p. 217–226 (2016).
[3] R. F. de Oliveira, et al., Adv. Func. Mater. 29, 1905375 (2019).
[4] F. Torricelli, et al., Nat. Rev. Methods Primers 1, 66 (2021).