Optical and Photoelectronic Properties of MoS₂/Graphene Oxide Nanocomposites for Visible-Light Photodetection

Abstract Two-dimensional (2D) MoS₂ and MoS₂/graphene oxide (GO) nanocomposites were synthesized via a chemical bath deposition (CBD) method and systematically explored for visible light photodetection. Structural and microscopic characterizations confirmed the formation of hexagonal-phase MoS₂ nanosheets and effective GO incorporation, accompanied by a reduction in crystallite size and an increase in lattice strain in the hybrid system. Optical absorption studies revealed a pronounced blue shift compared to bulk MoS₂, with the optical bandgap increasing from 2.2 eV for pristine MoS₂ to 2.5 eV for the MoS₂/GO nanocomposite (1:2 ratio), indicating strong quantum confinement effects. Photoluminescence measurements showed substantial quenching upon GO incorporation, suggesting suppressed electron-hole recombination and enhanced interfacial charge separation. Planar photodetector devices fabricated using MoS₂ and MoS₂/GO exhibited distinct wavelength- and intensity-dependent photoresponse across the visible spectrum (492-621 nm). The MoS₂/GO device consistently outperformed pristine MoS₂, delivering significantly enhanced photocurrent, responsivity, detectivity, and external quantum efficiency. At an illumination intensity of 45,000 lux, the photocurrent increased from 0.05×10⁻⁶ A for MoS₂ to 7.70×10⁻⁶ A for the MoS₂/GO nanocomposite. Temperature-dependent transport measurements yielded activation energies of ~0.09 eV (MoS₂) and ~0.08 eV (MoS₂/GO), indicating facilitated charge transport in the hybrid structure. These results demonstrate that controlled GO incorporation is an effective strategy for optimizing the optical and photodetection performance of MoS₂-based nanocomposites, making them promising candidates for scalable and cost-effective optoelectronic applications.