Modulating optical and electronic properties of Indium Selenide (In_xSe_y) compounds using polymer-based iongel gating.

Layered van der Waals two-dimensional semiconductor compounds based on Indium and Selenium (In_xSe_y) have attracted great attention in the research community in the last few years due to their bandgaps in the visible region, excellent carrier mobility, high in-plane anisotropy, and flexibility. Moreover, the possibility of high spin-orbit coupling due to the presence of heavy elements and robust ferroelectricity, such as in In₂Se₃, makes it a promising candidate for various spintronic devices. However, to effectively harness these materials and integrate them in optoelectronic devices for practical applications, it is important to be able to tune and manipulate their properties. We here demonstrate effective modulation of optical and electronic properties using Polyethylene oxide (PEO) and Lithium perchlorate (LiClO₄) based iongel gating.

Using high capacitance offered by these compounds, typically more than ten times than many solid-state dielectrics, we are able to effectively modulate the optoelectronic properties of In_xSe_y but by only applying a few volts of operating gating voltage. Furthermore, the highly transparent nature of iongel enabled us to fabricate a phototransistor whose device parameters such as responsivity could be tuned over a wide range of excitation wavelengths in the visible region. Our successful use of iongel as a gating medium further opens up opportunities to explore its effects on other interesting properties of In_xSe_y, for example, such as spin-orbit coupling.