Pulsed light sintering of silver nanoparticles for large deformation of printed stretchable electronics

Growth of printed electronics has increased the interest in the nanoparticle inks. Research on flexible electronics has expanded not only due to inherent benefits of producing flexible products but also for its high-throughput manufacturability, such as roll-to-toll (R2R) process. Conventional sintering methods cause microcracks and voids in the sintered nanoink film, which lead to subpar performance, and are not suitable for the high-throughput R2R production. Furthermore, these methods are incompatible with many polymer substrates used in flexible electronics due to their low thermal budget. In this study, we present an alternative method utilizing an intense pulsed light (IPL) with a xenon flash lamp to sinter silver nanoink on a polymer substrate. The IPL method is capable of selectively sintering the silver nanoink in milliseconds without damaging the polymer substrates. The silver nanoink was stencil printed on a polydimethylsiloxane (PDMS) specimen. Samples were prepared using five different sintering conditions and tested under uniaxial strain. Three IPL sintering conditions were compared against a non-sintered (NS) and an oven-sintered (OS) conditions. The IPL-sintered samples show a significant improvement in tensile test over NS and OS samples. Samples sintered at 20 J/cm² of flash energy density and 10 ms of duration were stretched up to 27% strain before losing electrical conductivity. Scanning electron microscopy (SEM) confirms these results showing a reduction in porosity of the sintered nanoink as compared to NS and OS samples. [Figure not available: see fulltext.]