High-performance, fast-response photodetectors based on hydrothermally synthesized V_1−<i>x</i>Mo_<i>x</i>Se₂ nanosheets

With the demand for wearable and low-energy consumption devices, it is essential to fabricate high-performance and fast-response photodetectors using an effective, easy and low-cost technique. In this regard, MoSe₂-based transition metal dichalcogenides are promising materials for their potential applications in future nanoscale electronic/optoelectronic devices. The current work demonstrates the optical, electrical, and photoresponsivity performance of V_1-<i>x</i>Mo_<i>x</i>Se₂ (<i>x</i> = 0, 0.05, 0.10, 0.15, 0.20) nanocomposites synthesized using a facile hydrothermal method with varying V and Mo contents. X-ray diffraction analysis was performed to investigate their polycrystalline structure. Raman study confirmed the existence of VSe₂ and MoSe₂ phases in the prepared samples. Bare VSe₂ shows a nano-flower-like morphology, whereas the Mo-doped V_1-<i>x</i>Mo_<i>x</i>Se₂ structure changed to nanosheets as verified from field emission scanning electron microscopy. The optical analysis showed the bandgaps of the synthesized samples varying between 1.2 eV and 2.5 eV. These low-bandgap materials play significant roles in optoelectronic devices like LEDs, solar cells, and photodetectors. The oxidation states of the different elements were probed using X-ray photoelectron spectroscopy. The <i>I</i>-<i>V</i> measurement showed better electrical conductivity. Photodetection measurements yield figures of merit such as sensitivity, responsivity, and detectivity values. A high <i>I</i>_on/<i>I</i>_off ratio is demonstrated by the time-dependent photo-response characteristics of the VSe₂ sample, which is remarkable for creating sensitive photodetectors.