Covalent functionalization of transition metal dichalcogenides with perylene for light harvesting devices

This study investigates the optical and electronic properties of eight two-dimensional transition metal chalcogenides (TMDs)-MoS₂, WS₂, MoSe₂, WSe₂, MoTe₂, WTe₂, MoO₂, and WO₂-covalently functionalized with perylene, forming zero-dimensional/two-dimensional hybrid materials. Comprehensive characterization was conducted using techniques including XPS, Raman, EDX, TEM, and AFM. Optical properties were assessed using UV-Vis-NIR absorption and photoluminescence spectroscopy, while electronic properties were examined through cyclic voltammetry and field-effect transistor devices. Notably, the spectroscopic signatures of isolated perylene predominate in the hybrid materials, while WSe₂ and MoSe₂ displayed a novel band in the near-IR region, and MoTe₂ exhibited enhanced conductivity. Perylene significantly boosted absorption between 400-600 nm, leading to remarkable improvements in the photo-response and responsivities showing values exceeding 2 × 10⁵% and 2 × 10⁴ mA W^-1, respectively. The presented hybrid materials rival the best examples of non-covalent functionalization, underscoring the potential of covalent functionalization as a powerful technique for further tailoring the optical and electronic properties of 2D materials.