Printed/Flexible Conductive Patterns Using Versatile Sintering Methods of Metal Nanoparticles

This project aims to advance printed and flexible electronics, an essential foundation for next-generation smart devices, wearables, sensors, and internet-of-things (IoT) applications. In fabrication of these electronics, metal nanoparticle (NP) inks are widely utilized to create printable conductive patterns. To achieve high electrical conductivity, the printed metal NP patterns must undergo a sintering process that removes organic compounds and aids in the consolidation of metal NPs. However, conventional thermal sintering requires high temperatures that often cause critical deformation and thermal degradation of the underlying flexible polymer substrates. This research addresses this fundamental issue by introducing a versatile hybrid sintering process that combines thermal treatment with laser irradiation. This synergistic method enables efficient ink consolidation and organic compound removal without damaging the heat-sensitive plastic base. By delivering highly stable and reliable conductive patterns through an eco-friendly, low-cost process, this project serves the national interest by advancing industrial prosperity and technological competitiveness. Beyond its technical contributions, the award supports education by integrating cutting-edge research into university coursework, providing undergraduate research opportunities, and creating STEM outreach activities through university programs to foster a highly skilled workforce. The primary goal of this project is to establish the fundamental scientific principles and mechanistic understanding governing a hybrid sintering process that combines thermal treatment and laser irradiation for printed metal NP inks. The specific objectives are to elucidate synergistic sintering mechanisms, determine the correlation among sintering variables, microstructure evolution, and chemical composition, and achieve metal conductive patterns exhibiting excellent electrical and mechanical performance on polymer substrates. The methodology integrates robust experimental and computational approaches. The project will investigate the coupled effects of low-temperature thermal sintering and laser irradiation on organic substance removal and NP consolidation. Molecular dynamics (MD)-based simulations will model nanoscale melting, atomic diffusion, and microstructure evolution during sintering to predict material morphology and phase changes. Furthermore, the research will identify the effects of sintering parameters on microstructure, chemical composition, and mechanical reliability. Finally, the practical applicability of the optimized conductive patterns will be demonstrated through the fabrication and testing of flexible electronic devices, specifically radio frequency identification (RFID) tags and organic thin film transistors (OTFTs), establishing a predictable framework for high-throughput flexible electronics manufacturing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.