Tailored Nitrogen-Doped Laser-Induced Graphene on Novel Synthesized Cross-Linked Aromatic Polyimides for Targeted Applications

Laser-induced graphene (LIG) is most often produced from commercial Kapton; the properties of LIG are inherently linked to those of the polymer substrate, which results in a limited field of applications for LIG on Kapton. This study demonstrates that tailored properties of LIG, including nitrogen doping, which is favorable for electronic applications, can be achieved by using synthesized cross-linked polyimides (PIs) as substrates for graphene induction. Three amorphous polyimides containing 4-[(4-aminophenyl)sulfonyl]aniline (PI-APSA), 1,2-diaminoethane (PI-EDA), and urea (PI-Urea), as crosslinkers, were prepared from different diamines and maleic anhydride, and subsequently used as substrates to produce in situ nitrogen-doped LIG. The resulting materials were comprehensively characterized and compared with LIG on Kapton. Raman spectroscopy confirmed lower defect densities and higher crystallinity than in LIG on Kapton, while sheet resistance was up to three times smaller. The LIG with PI-EDA showed the highest nitrogen content and a specific areal capacitance of 3.1 mF/cm2, which is more than an order of magnitude higher than that of LIG/on Kapton, highlighting its strong potential for energy storage devices. PI-APSA-based LIG exhibited the best adhesion and lowest sheet resistance, making it suitable for wearable electrodes, whereas PI-urea-based LIG maintained hydrophilicity. Thus, chemically tailored polyimides enable the formation of nitrogen-doped LIG with tunable interfacial properties, higher structural order, and improved electrical and electrochemical performance compared to commercial Kapton.