TiS₃ nanosheets are promising candidates for future polarization optics applications due to their strongly anisotropic optical properties.

Liquid-phase exfoliation is a technique capable of producing large quantities of two-dimensional materials in suspension. Despite many efforts in the optimization of the exfoliation process itself, not much has been done towards the integration of liquid-phase-exfoliated materials in working solid-state devices. In this article, we use dielectrophoresis to direct the assembly of liquid-phase-exfoliated TiS₃ nanoribbons between two gold electrodes to produce photodetectors working in the visible region. Through electrical and optical measurements we characterize the responsivity of the device and we find values as large as 3.8 mA W⁻¹, which are more than one order of magnitude higher compared to state-of-the-art devices based on liquid-phase-exfoliated two-dimensional materials assembled by drop-casting or ink-jet methods.

In two-dimensional materials research, oxidation is usually considered as a common source for the degradation of electronic and optoelectronic devices or even device failure. However, in some cases a controlled oxidation can open the possibility to widely tune the band structure of 2D materials. In particular, we demonstrate the controlled oxidation of titanium trisulfide (TiS₃), a layered semicon-ductor that has attracted much attention recently thanks to its quasi-1D electronic and optoelectron-ic properties and its direct bandgap of 1.1 eV. Heating TiS₃ in air above 300 °C gradually converts it into TiO₂, a semiconductor with a wide bandgap of 3.2 eV with applications in photo-electrochemistry and catalysis. In this work, we investigate the controlled thermal oxidation of indi-vidual TiS₃ nanoribbons and its influence on the optoelectronic properties of TiS₃-based photodetec-tors. We observe a step-wise change in the cut-off wavelength from its pristine value ~1000 nm to 450 nm after subjecting the TiS₃ devices to subsequent thermal treatment cycles. Ab-initio and many-body calculations confirm an increase in the bandgap of titanium oxysulfide (TiO_2-xS_x) when in-creasing the amount of oxygen and reducing the amount of sulfur.