Two new publications on novel lightweight conductors based on graphene and graphite

20.Feb.2025   Reseach News

We recently published two new publications on novel lightweight conductors based on graphene and graphite. The paper by Niemann et al. focusses on the improvment of the electrical conductivity of graphitic films by transition metal additives. Graphite based conductors are promising low cost and light-weight alternatives to copper but current challenges are among others the improvement of the conductivity of graphite films (GF). Therefore, in this work the influence of copper(II) chloride and nickel(II) chloride on the graphitization of graphene oxide and the electrical conductivity of the resulting GF was studied. The electrical conductivity was measured at different scales by contactless eddy current method and four point probe scanning tunneling microscopy transport measurements. The macroscopic and nanoscopic transport measurements were complemented by network-based simulations, which allowed us to estimate the microscopic material properties of the GF with and without additives.

A second recent paper by Stevens et al. highlights the record conductivity of drop-casted graphen-based films. In this work, we report a stage-controlled wafer level drop casting technique of thin graphene paths from a water based, additive free graphene dispersion. The graphene dispersion was cast onto wafer substrates up to 8 in. in size and annealed at 300 °C, achieving 0.14 × 10⁶ S/m with controllable path thicknesses down to 30 nm. The electrical conductivity can be significantly increased to up to 3.5 × 10⁶ S/m by gas-phase doping using AlCl₃. We discuss a doping experiment, resulting in a gradual increase of conductivity between 2 and 30 times, underlined by EDX, Raman spectroscopy and profile measurements. Further, we have modelled the graphene paths as an idealized layered system with many flakes per layer, connected all flakes to form a conductor network, and finally solved this network via nodal analysis. The reported results surpass previously shown conductivities for dispersion casting of graphene by over an order of magnitude, offering a sustainable alternative to replace metal-based conductors in electronic devices.