Modeling nanoscale temperature gradients and conductivity evolution in pulsed light sintering of silver nanowire...

Sintering of metal nanowire (NW) networks on transparent polymers is an emerging approach for fabricating transparent conductive electrodes used in multiple devices. Pulsed light sintering is a scalable sintering process in which large-area, broad-spectrum xenon lamp light causes rapid NW fusion to increase network conductivity, while embedding the NWs in the polymer to increase mechanical robustness. This paper develops a multiphysical approach for predicting evolution of conductivity, NW fusion and nanoscale temperature gradients on the substrate during pulsed light sintering of silver NWs on polycarbonate. Model predictions are successfully validated against experimentally measured temperature and electrical resistance evolution. New insight is obtained into the diameter-dependent kinetics of NW fusion and nanoscale temperature gradients on the substrate, which are difficult to obtain experimentally. These observations also lead to the understanding that NW embedding in intense pulsed light sintering (IPL) can occur below the glass transition temperature of the polymer, and to a new differential thermal expansion-based mechanism of NW embedding during IPL. These insights, and the developed model, create a framework for physics-guided choice of NWs, substrate and process parameters to control conductivity and prevent substrate damage during the process.