Thermally reduced graphene oxide films as flexible lateral heat spreaders†
A thermally reduced graphene oxide film (r-GOF), with tailorable micro-structures and macro-properties, is fabricated by annealing a filtrated graphene oxide film (GOF) in a confined space. The structural evolution of the film at different annealing temperatures is systematically investigated, and further correlated to the thermal conductivity and mechanical performances. With the increase of temperature, more oxygen-containing functional groups are removed from the film by a simultaneous conversion from sp3 to sp2 carbon in the graphitic lattice. As the temperature reached 1200 °C, the r-GOF achieves an ultrahigh thermal conductivity of ca. 1043.5 W m−1 K−1, while 1000 °C is a critical temperature in enhancing the thermal conductivity. Moreover, G1200 exhibits excellent mechanical stiffness and flexibility with a high tensile strength (13.62 MPa) and Young's modulus (2.31 GPa). The combined conductivity and mechanical performances render the r-GOFs promising materials as flexible lateral heat spreaders for electronics.