Charge Transport and Noise in PVP-Coated Silver Nanowire Networks: Implications for Neuromorphic Applications

Neuromorphic materials, which emulate biological neural networks, are gaining attention for next-generation computing systems. Networks of PVP-coated silver nanowires (Ag NWs) are especially promising, making it crucial to study their charge transport mechanisms to optimize their performance and reliability in neuromorphic devices. In this study, we investigate the transport properties of PVP-coated Ag nanowire networks by studying the behavior of the current and the associated noise as a function of temperature and applied electric field. Time-domain noise studies reveal current fluctuations that scale linearly with the average current, indicative of conductance fluctuations, while frequency-domain analysis shows 1/f noise with exponents ranging from 1.3 to 1.5. Further transport studies, focusing on the temperature dependence of conductance, demonstrate variable-range hopping behavior with a localization length comparable to the thickness of the PVP coating. The mechanism underlying 1/f noise in the network can be understood within a dynamic random resistor network model, where phonon-assisted hopping or tunneling activates and rearranges conduction pathways, while ion migration modifies local electric fields and trap-state distribution within the PVP layer. This finding emphasizes the critical role of the thin polymer layer in modulating the charge transport through the nanowire network. The combined insights from noise and transport analyses reveal the significant influence of the PVP coating on charge dynamics, offering valuable guidance for the design and optimization of neuromorphic materials based on metal nanowire networks.