Pyrolytically Modified Polyacrylonitrile‐Covalently Grafted MoS₂ Nanosheets for a Nonvolatile Rewritable Memory Device

Abstract The electrical conductivity of laterally ordered polyacrylonitrile (PAN) can be improved by pyrolytic modification. Newly synthesized MoS₂ nanosheets covalently grafted with PAN (MoS₂‐PAN) do not exhibit any electrical switching and memory effect in an indium tin oxide (ITO)/MoS₂‐PAN/Au device under applied bias voltages. After annealing at 220 °C for 4 h, the resultant pyrolytically modified product “pyro‐MoS₂‐PAN” shows good nonvolatile rewritable memory performance, with a large ON/OFF current ratio of 4 × 10⁴ and lower switching on and off voltages of −1.09 and 1.24 V. Highly reproducible memory I–V loops of more than 60 consecutive cycles are achieved without clear degradation of the ON and OFF states. The first oxidation potential of pyro‐MoS₂‐PAN is cathodically shifted to over 530 mV lower than that of MoS₂‐PAN, indicating the higher hole injection of pyro‐MoS₂‐PAN when compared to MoS₂‐PAN. As expected, the nonannealed MoS₂/PAN blend‐based device does not show any memory effect under the same experimental condition. After annealing at 220 °C for 4 h, the blends exhibit unstable electrical switching and rewritable memory performance.