Systematic Study of Photothermal Nanomaterial–Assisted Laser‐Induced Graphene Formation

Laser‐induced graphene (LIG) enables direct, maskless graphitization of polymer substrates through localized photothermal heating, providing a rapid, scalable platform for flexible electronics. While nanomaterial coatings have been reported to enhance laser absorption and reduce the laser power required for LIG formation, a quantitative understanding of photothermal heating dynamics, formation thresholds, and morphology remains limited. Here, we systematically investigate photothermal nanomaterial–assisted LIG formation using a CO ₂ laser on polyimide (PI) films coated with multiwalled carbon nanotubes (MWCNTs), single‐walled carbon nanotubes (SWCNTs), graphene oxide, and MXene. Time‐resolved infrared thermography reveals distinct nanomaterial‐dependent heating dynamics, with SWCNT coatings exhibiting the earliest onset of rapid temperature rise. The laser power threshold for LIG formation decreases with increasing nanomaterial loading. Cross‐sectional scanning electron microscopy demonstrates that nanomaterial‐assisted LIG formation suppresses substrate swelling and yields thinner, more surface‐confined graphitic layers. Based on these observations, we propose a mechanistic model for nanomaterial‐assisted LIG formation. Finally, after transfer onto polydimethylsiloxane films, the LIG exhibits nanomaterial‐dependent strain sensitivity, with MWCNT‐assisted LIG achieving the highest gauge factor (152) at 20% strain, 1.45 times greater than that of bare PI–derived LIG, due to distinct LIG morphology. These findings provide fundamental insights and design guidelines for controllable, low‐power LIG fabrication.