pH effect in Langmuir–Blodgett self-assembly of MoS2 and WS2 thin films

Abstract

We reported Langmuir–Blodgett films of molybdenum disulphide and tungsten disulfide and studied the formation of $${\text{Mo}}{\text{S}}_{2}$$ MoS 2 and $${\text{WS}}_{2}$$ WS 2 layers. The effect of the subphase pH is investigated. Also, the influence of the subphase conditions on the number of layers was reported. By varying the pH of the buffer solution subphase, the solvent-to-nanoparticle interaction is changed and the compression of the layer during deposition is influenced. The stacking of the $${\text{Mo}}{\text{S}}_{2}$$ MoS 2 and $${\text{WS}}_{2}$$ WS 2 crystalline structure under the influence of subphase pH and the material concentration were investigated. Langmuir layers assembly is a useful method to manipulate the distribution of $${\text{WS}}_{2}$$ WS 2 and $${\text{Mo}}{\text{S}}_{2}$$ MoS 2 . Successful deposition of dichalcogenides at the air–water interface on silicon substrate was performed using Balance Langmuir–Blodgett technique. The characterization of $${\text{WS}}_{2}$$ WS 2 and films $${\text{Mo}}{\text{S}}_{2}$$ MoS 2 with X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy was carried out.