Laser-Carbonized Graphene and Lignin Films for Sustainable Transient RFID Electronics

Abstract

The growing problem of electronic waste calls for new materials that are sustainable and easy to recycle. This thesis focuses on developing conductive films for transient and flexible electronics using two different material systems.

In the first part, cellulose paper was used as a biodegradable base. Three types of coatings were prepared: (i) graphene oxide (GO), (ii) GO with ascorbic acid (AA) as a reducing agent, and (iii) GO with a mixture of ascorbic acid and sodium lignosulfonate (Na-Lgs) to provide extra carbon content. After coating, the samples were treated with a laser to create conductive patterns directly on the cellulose. This study shows that cellulose can serve as a compostable material for electronics while still offering useful electrical properties.

In the second part, polyethylene terephthalate (PET) films were coated with compressible flow exfoliated (CFE) graphene. PET provided strength and flexibility, while the graphene coating gave an initial conductivity that was further improved by laser carbonization. The PET/CFE system achieved very low sheet resistance, with the best value recorded at 16.17 Ω/sq, showing excellent electrical performance compared to many earlier studies.

To evaluate both systems, several techniques were used: SEM to study the surface and cross-section of the films, TGA to test thermal stability, Raman spectroscopy to analyze graphitic structure, FTIR to confirm chemical changes, and sheet resistance measurements to check electrical performance. Overall, the results show two promising directions: cellulose-based films for biodegradable and eco-friendly devices, and PET/CFE graphene films for high conductivity and robust performance. In particular, the PET/CFE graphene system, with its low sheet resistance, shows strong potential for further development towards commercial RFID tags and other high-performance flexible electronic devices.