Experimental and simulation study on space charge characteristics of epoxy resin filled with graphene oxide

Graphene has attracted much attention due to its advanced properties. In previous work, the relationship between temperature and the conductivity of epoxy-based nanocomposite filled with graphene oxide has been experimentally studied. To understand the charge transport behaviour, the space charge characteristics at different temperatures and field strengths are measured with an improved pulsed electroacoustic measurement system, which is designed for high-temperature space charge measurement. From the measurement results, epoxy resin (ER) filled with multi-layer graphene oxide (MGO/ER) shows suppressed charge migration while ER filled with single-layer graphene oxide (SGO/ER) shows a hetero charge accumulation, which is assumed to be caused by the partial reduction of graphene oxide to graphene. Compared to pure ER, the apparent mobility of the nanocomposites is smaller while the trap depth and number of trapped charges are larger, which is probably caused by the introduction of traps. In the simulation, the relationship between mobility, trap depth, trap density and charge distribution are firstly studied. Then the calculated values of mobility and trap depth are given to the parameters to compare the simulated charge profiles with experiment results. The simulation results agree well qualitatively with the experimental results, giving some support for the proposed explanations.