Thermally Controlled Localized Porous Graphene for Integrated Graphene‐Paper Electronics

Porous graphene (PG) devices fabricated in situ from polyimide (PI) adhered onto paper substrates provide a cost‐effective and recycling‐friendly alternative to re‐engineer paper for liquid‐based power sources and sensors. However, paper is generally damaged due to heating during the fabrication of PG devices. Here integrated graphene‐paper electronics with exceptional thermal control through the proposed thermally localized laser graphitization (LLG) process is demonstrated, employing optimized ultrafast laser writing. LLG enables in situ fabrication of localized porous graphene (LPG) devices (>1775 K) on 65 µm thick PI tape adhered to paper without heating above 348 K. Laser parameters for LLG are predicted using an analytical temperature model and validated experimentally. The LLG is demonstrated by fabricating liquid electrolyte LPG micro‐supercapacitors and humidity sensors on liquid susceptible paper. It is envisaged that the scientific concepts proposed and demonstrated here will expedite the development of low‐cost, scalable, and chemically robust LPG devices on thermally sensitive substrates. The thermally localized laser graphitization (LLG) process enables in situ fabrication of robust localized porous graphene (LPG) devices on thermally sensitive paper substrates, through a one‐step femtosecond laser writing process. LLG parameters are predicted from an analytical temperature model and experimentally validated. LPG humidity sensors and micro‐supercapacitors that protect hygroscopic paper from liquids are thus demonstrated as integrated graphene‐paper electronics.