Langmuir–Blodgett assembly for controlled deposition of GO, rGO, MoS2, and WS2 thin films

Abstract Two-dimensional (2D) materials such as graphene oxide (GO), reduced graphene oxide (rGO), molybdenum disulfide (MoS 2 ), and tungsten disulfide (WS 2 ) have exceptional electrical, optical, and mechanical properties that make them promising for next-generation optoelectronic and sensing technologies. However, creating homogeneous and reproducible thin films remains difficult. In this study, we employed the Langmuir–Blodgett (LB) technique to transfer GO, rGO, MoS 2 , and WS 2 films onto Si/SiO 2 substrates. We successfully formed stable monolayers at the subphase as shown by clear compression isotherms, utilizing 150 μL of 0.1 mg/mL dispersions and subphase pH levels of 4.5 to 5.5 for GO/rGO and 7.0 to 7.4 for MoS 2 /WS 2 . Scanning Electron Microscopy (SEM) analysis revealed highly uniform films, covering about 80% of the substrate, while Atomic Force Microscopy (AFM) confirmed nanoscale continuity, with roughness values of R a = 1.2 to 1.8 nm, Rq = 1.5 to 2.3 nm, and thicknesses ranging from 1 to 4 nm for GO/rGO and 0.7 to 1.4 nm for MoS 2 /WS 2 . Structural analyses confirmed the quality of the films: FTIR showed successful reduction of oxygenated groups in rGO; Raman spectra displayed characteristic D/G bands with I(D)/I(G) ratios of 0.93 (GO) and 1.12 (rGO); and XRD revealed the (002) reflection of rGO at 2θ ≈ 25° with an interlayer spacing of 0.376 nm, indicating 8 to 12 stacked layers, while MoS 2 and WS 2 diplayed their characteristic E 2 g 1 and A₁g vibrational modes with peak separations of about 26 and 67 cm −1 , respectively, this confirms that they have multilayer crystalline structures. The XRD measurements reveal that MoS₂ and WS 2 maintained their (002) reflections, which are a clear sign of layered stacking. These findings demonstrate that LB deposition allows precise control over how nanosheets are packed, the number of layers, and the uniformity of the films, all while maintaining the morphological and structural characteristics of each 2D material. Thanks to this reproducibility, nanoscale precision, and compatibility with semiconductor processing, the LB technique presents a robust pathway for integrating 2D materials into the next generation of optoelectronic devices, photodetectors, and micro/nanofabricated systems.