Multiscale Modeling of Sintering-Driven Conductivity in Large Nanowire Ensembles.

Abstract

Thermally driven sintering is widely used to enhance the conductivity of metal nanowire (NW) ensembles in printed electronics applications, with rapid nonisothermal sintering being increasingly employed to minimize substrate damage. The rational design of the sintering process and the NW morphology is hindered by a lack of mechanistically motivated and computationally efficient models that can predict sintering-driven neck growth between NWs and the resulting change in ensemble conductivity. We present a de novo modeling framework that, for the first time, links rotation-regulated nanoscale neck growth observed in atomistic simulations to continuum conductivity evolution in inch-scale NW ensembles via an analytical neck growth model and master curve formulations of neck growth and resistivity. This framework is experimentally validated against the emergent intense pulsed light-sintering process for Ag NWs. An ultralow computational effort of 0.2 CPU-h is achieved, 4-10 orders of magnitude reduction as compared to the state of the art. We show that the inherent local variation in the relative NW orientation within an ensemble drives significant junction-specific differences in neck growth kinetics and junction resistivity. This goes beyond the conventional assumption that the neck growth kinetics is the same at all the NW junctions in an ensemble, with significant implications on how nanoscale neck growth affects ensemble-scale conductivity. Through its low computational time, easy and rapid recalibration, and experimental relevance, our framework constitutes a much-needed foundational enabler for a priori design of the sintering process and the NWs.