Considering these challenges, we explored a promising solution utilizing silver nanowires (AgNWs) as the conductive material, coated onto a regenerated cellulose (RC) substrate through gravure printing. The RC substrate, derived from bio-based raw materials, offers superior degradability and enables sustainable end-of-life pathways such as degradation. Gravure printing is also more energy-efficient than sputtering. Additionally, AgNWs not only use non-critical silver but also exhibit higher conductivity and greater stretchability than ITO, expanding potential applications in soft electronics. However, the synthesis of AgNWs and RC remains solvent- and energy-intensive. Therefore, this study employs life cycle assessment (LCA) to provide holistic understanding of the potential environmental impacts of AgNWs-coated RC films compared to ITO-coated PET films. In addition, various green design strategies have been explored to optimize AgNWs and RC film production from a sustainability perspective.
Our preliminary results show that without green design, the environmental impacts of AgNWs-coated RC films are up to 16 times higher than those of ITO-coated PET films across various impact categories. The primary contributor to these impacts is the synthesis of RC substrate. However, the environmental performance of RC substrate can be substantially improved by green design, with an average 97% reduction in all impact indicators. Our green design strategies include improving material utilization efficiency by recovering solvents and enhancing the energy efficiency. Moreover, AgNWs inks present lower environmental burdens than those of ITO target, even without green design. This advantage stems from the higher conductivity of silver, which allows for a lower material requirement compared to ITO for achieving similar conductivity in TCF. Additionally, gravure printing has lower energy demand than sputtering for ITO. All these improvements result in lower environmental impacts of green-designed AgNWs-coated RC film compared to ITO-coated PET films.
Our research addresses the lack of environmental analysis for emerging AgNWs-coated RC films, which are being investigated at the laboratory scale. We demonstrated that the existing synthesis process of AgNWs-coated RC films is not environmentally competitive compared to ITO-coated PET films. However, this can be improved by green design strategies, including waste solvent recovery and energy efficiency optimization. This study provides insights into the possible scalability of AgNWs-coated RC films from an environmental perspective. Moreover, our findings can inform the design of other AgNWs- or RC-based products, such as electronic skin and agricultural mulch.