Synthesis of nanocrystalline molybdenum disulfide films and studies of their structure, spectral and photoelectrical properties

An approach for preparing MoS2 films in mild conditions is described, which is based on producing the suspensions of nanocrystalline MoS2 particles in organic solvent via exfoliation of MoS2 crystals, followed by the deposition of these suspensions onto substrate. According to X-Ray diffraction data, acetonitrile suspensions yield highly oriented films with the basal planes of MoS2 crystallites being mainly oriented in the plane parallel to the substrate. Atomic force microscopy examination revealed changes in the film surface topography under variation of the film thickness, which varied in the range of 0.03–2.2 μm. The optical absorption spectra of the obtained MoS2 films were found to resemble those of thin natural MoS2 single crystals. Dark conductivity of the films with the thickness of d = 0.12–2.2 μm was determined to be ~ 10− 3 S∙cm− 1 at 300 K. Experimental data on the conductivity in the temperature range of 10–300 K were fitted to Mott function for 3D variable-range hopping. The synthesized MoS2 films were found to be photosensitive in the range of 300–800 nm. They provided the value of reduced photocurrent density of about 7∙10− 4 (A∙cm)/(WV) under photoexcitation at 575 nm.