Cradle-to-gate life cycle assessment of nano-enabled all-carbon recyclable electronic (ACRE) materials

Abstract

The fabrication of semiconductor devices, particularly those used in flat-panel displays, is one of the significant climate-change challenges identified by the US Environmental Protection Agency (EPA) due to the associated greenhouse gas emissions. This study investigates the potential of all-carbon recyclable electronic (ACRE) materials as an innovative, eco-friendly alternative to conventional semiconductor materials in thin-film transistor (TFT) production. Using ink-processable materials such as crystalline nanocellulose (CNC), carbon nanotubes (CNT), and graphene, reduced greenhouse gas (GHG) emissions and enhanced material recyclability, can be realized. A cradle-to-gate Life Cycle Assessment (LCA) was conducted to evaluate the environmental performance of ACRE-based TFTs compared to conventional transistors across six scenarios that include different CNT production methods. The results demonstrate the baseline ACRE scenario consistently achieves the lowest environmental impact, with the High-Pressure Carbon Monoxide (HiPco) method emerging as the most sustainable production approach. Although the Ink contributes only minimally to the final product—given its very small mass relative to the total glass weight—HiPco still performs better than the Arc and CVD methods by approximately 0.1% and 0.2%, respectively. However, key challenges remain, including the energy-intensive nature of material synthesis and the environmental impacts associated with the glass substrate and ink preparation processes. The findings underscore the importance of targeted material processing and substrate production improvements to reduce environmental burdens further. Indeed, CNTs, CNC, and graphene, which are the base materials for printing the transistor on glass, contribute more than 40% to the total impact in multiple environmental categories. Moreover, the study highlights the need for a holistic approach to TFT design and manufacturing, integrating energy efficiency and sustainable material selection. The sensitivity analysis shows how a ±50% change in energy consumption can influence the environmental impact, particularly for the ionizing radiation and land use categories, which exhibit sensitivities of approximately 30% and 25%, respectively. Future work could expand this analysis by conducting a cradle-to-grave LCA to assess the impacts of the entire life cycle, as use and end-of-life stages. This research establishes a foundation for advancing ACRE technologies and underscores their potential to mitigate the challenges posed by e-waste, paving the way for more sustainable practices in the electronics sector.