Investigations on laser interaction of polyimide for synthesis of laser induced graphene towards triboelectric nano-generation applications

Abstract

Graphene, much discussed for probable replacement of silicon age in the electronics and energy harvesting industry, has witnessed a sharp rise in research. The latest technique of polyimide carbonization by laser patterning has received much attention because of its capability to create varieties of functional materials and flexible devices. The requirement of graphene demands larger volume production where Laser-Induced Graphene by consideration of pulse overlap could prove to be the solution if a recipe is prepared through appropriate optimization. The present study focused on the CO2 laser (λ=10.6 µm) interaction with polyimide by generating a raster pattern with varying pulse overlap in the linear direction. The raster pattern is fabricated at different laser energies and pulse overlap with a constant 30% line overlap between two consecutive lines, in the lateral direction, for synthesizing LIG at relatively low laser power. Various combinations of laser fluences (46 J cm-2 , 56 J cm-2 , 66 J cm-2 ) and pulse spot overlap (60%, 70%, and 80%) were used for the polyimide carbonization. Both experimental and numerical simulation (using ComsolTM) results present an insight that optimal control of laser pulse overlap shows a significant effect on crystallinity and electrical resistivity of synthesized graphene. The macroscopic quality of the raster pattern is investigated through the optical microscope. Detailed Raman Spectro microscopic analysis is carried out to study the defect to graphenization ratio and its impact on the properties of graphene synthesized. The pulse overlaps the photo-thermal model, and its finite element analysis implementation presents a better understanding towards optimizing the complicated but promising technique towards synthesizing laser-induced graphene. Finally based on the optimized parameters, a flag fluttering device with LIG as an electrode for Kapton Polyimide which is a tribo-negative material is used . Aluminum as a tribo positive layer is used and using continuous wind energy, nano-energy is generated in the range of +40 V to -40 V and some peaks even touching around 80 V as well and current is generated in the range of +4 µA to -4 µA.