Laser-synthesis of conductive carbon-based materials from two flexible commercial substrates: A comparison

Abstract

One of the key challenges in the field of flexible electronics relies on finding conductive materials that can withstand bending and stretching stresses while maintaining their performance. In this context, this work presents a comparative study of laser-induced conductive materials from the direct laser-scribing of two commercial flexible films: the benchmark Kapton® HN polyimide (PI) precursor and the UltemTM 1000 polyetherimide (PEI) alternative contender. The synthesis process on both materials is optimized in terms of electrical conductivity using a high-performance galvanometric laser with a wavelength of 532 nm for the fabrication of multiple samples at different laser powers and speeds. The samples are structurally characterized using Scanning Electron Microscopy (SEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and Fourier-Transform Infrared Spectroscopy (FTIR) aiming at understanding the chemical and physical changes of the ablated material. The results demonstrate that the proposed setup is feasible for the synthesis of uniform and reliable conductive patterns on the surface of both substrates with high reproducibility. In particular, it is proved that PEI is more suitable precursor for flexible electronics applications which demand high electrical conductivity, leading to a sheet resistance of 3.62 ± 0.35 Ω/sq at 0.8 W and 5 mm/s once the laser-synthesis process is optimized (against the 6.04 ± 0.63 Ω/sq at 0.6 W and 5 mm/s offered by the LIG on PI). The performance of both laser-induced patterns as electrodes for the fabrication of electrochemical capacitors is also studied and compared in terms of areal specific capacitance.