Photo-switching operation of MoS 2 field effect transistor by photoisomerization of azobenzene in solution delivered on a microfluidic platform.

Combining the photoisomerization of molecules with an electrical device is important for developing optoelectronic devices. Field effect transistors (FETs) with atomically thin channels are suitable for this purpose because the FET properties respond to chemical changes in molecules. Since the photoisomerization wavelength of the switching molecules can be tuned, complex logic operations can be realized if a specific molecule is delivered to the target FET of an integrated circuit. However, conventional techniques for transferring molecules, such as drop casting and sublimation, cannot efficiently realize this goal. In this study, we fabricated a MoS 2 FET device combined with a microfluidic platform, wherein the MoS 2 channel was in contact with the flow of an azobenzene solution in isopropyl alcohol as the solvent. UV radiation (365 nm) and thermal relaxation realize the cycle of trans- and cis-azobenzene states and the switching of the substantial FET properties. This study demonstrated the feasibility of using the solution for optical switching of the MoS 2 -FET, which can realize quick phase changes in the molecule and the delivery of the molecule to the target FET by a microfluidic platform.