Temperature-dependent electron transport in a composite film of reduced graphene oxide:MoS2 nanoflakes

Composites formed by reduced graphene oxide (rGO) and molybdenum disulfide (MoS2) are considered promising for applications such as nanoelectronics, electrochemical sensors, and catalysis. In this work, the temperature dependence of resistance R(T) of rGO-MoS₂ composite film was measured in the 5–290 K range and compared with that obtained for rGO film. It was found that the R(T) dependence of the rGO-MoS₂ composite film showed semiconducting behavior as the resistance increased at temperature lowering. The analysis of the R(T) dependence revealed that at low temperatures (from 5 to 166 K) the electron transport in the composite is governed by Efros-Shklovskii variable range hopping model (ES VRH). The higher temperature range (from 166 K to room temperature) was described in the framework of the 2D Mott VRH model as well as power-law dependence. Fitting the R(T) dependence of rGO-MoS₂ composite to curves calculated from these models allowed us to estimate the parameters of the electron transport such as localization length, density of localized states, and the width of the Coulomb gap. The values of these parameters are slightly different from those obtained for the rGO film. This small difference, similarity in the behavior of R(T) dependences, and applicability of the same transport models for rGO-MoS₂ and rGO samples indicate that electron transport in the composite is determined by the inherent conductivity of rGO nanosheets while the presence of MoS₂ nanoflakes can affect their ordering, local dielectric environment and thus electron transport parameters.