Flame-retardant tuned chitosan for high-performance laser-induced graphene toward biodegradable flexible electronics

One-step Laser-induced graphene fabrication is achieved via chitosan modified with trimethyl phosphate and glycerol. • The modified film achieves a high carbon residue of 35.3% and low sheet resistance of 23.7 Ω/sq. • The fabricated LIG serves as a multifunctional platform for temperature sensors, supercapacitors, and TENGs. • TMP-improved flame retardancy enables one-step laser graphitization while preserving flexibility and biodegradability. Chitosan (CS), one of the most abundant natural polymers on Earth, is a potential biodegradable precursor for Laser-induced graphene (LIG) fabrication. Nevertheless, pure CS and its derivatives often face challenges regarding insufficient mechanical properties or poor conductivity during one-step laser graphitization. To address these issues, this work proposes a novel modification strategy utilizing trimethyl phosphate (TMP) as a flame retardant and glycerol as a plasticizer for CS composite films (CTM). The incorporation of TMP significantly enhanced the thermal stability of the CS films, resulting in a high carbon residue yield of 35.3% at 750 °C. Through the optimization of laser scribing parameters, the resulting CTM-LIG flexible films achieved a sheet resistance as low as 23.7 Ω/sq. Leveraging the CTM-LIG flexible films fabricated via one-step CO₂ laser scribing, we successfully constructed various proof-of-concept green electronic devices, including a flexible temperature sensor with a rapid response time of 460 ms, a supercapacitor (SC) with high cyclic stability (99.1% capacity retention after 5000 cycles), and a triboelectric nanogenerator delivering a maximum power density of 277 mW/m 2 . Collectively, these results and proof-of-concept demonstrations establish CTM-LIG as a versatile multifunctional platform for sustainable transient electronics via a simple and scalable one-step laser fabrication strategy. Download: Download high-res image (113KB) Download: Download full-size image