Charge Transport at the Interface between Graphene Oxide and Silk in Highly Flexible Commercial Silk-Based e-Textile Treated at High Temperatures

Graphene oxide (GO)-coated silk-based electronic textiles (e-textiles) are of great interest and have high potential because of their advantages, including high electrical conductivity and flexibility. Although heat treatment of the GO-coated textiles at high temperatures results in e-textiles with high electrical conductivity, flexibility and structural stability are not guaranteed. Here, we demonstrate heat-treated GO-coated silk (HGS) at high temperatures (HTTs; 500, 600, 700, and 800 ?) with superior flexibility. For HGS800, the resistance change during bending remained under 1% even after 5000 cycles. We also investigated the charge transport mechanism of the HGSs and the interface between GO and the silk. The temperature-dependent resistivity of the HGSs from 8 to 300 K was clearly explained by the fluctuation induced tunneling model for all HTTs. The temperature-dependent resistance of the interface follows multidimensional variable range hopping. The conducting behavior of the HGSs was interpreted to be due to structural changes induced by HTT, based on scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction.