Laser-Induced Hydrothermal Growth of Iron Oxide Nanoparticles on Diverse Substrates for Flexible Micro-Supercapacitors

State-of-the-art microdevice fabrication requires patterned growth of functional nanomaterials on the desired position of the desired substrate. However, it is challenging, particularly in conventional hydrothermal synthesis, due to difficulties generating a local high-temperature field at the desired place. We introduce a laser-induced hydrothermal growth (LIHG) process for the rapid and selective synthesis of iron oxide nanoparticles (NPs). The substrates absorb the laser energy to generate a local high-temperature field necessary for the growth of iron oxide NPs. On various substrates, a dome-like structure comprising many iron oxide NPs is selectively synthesized within a localized temperature field. The LIHG process has several advantages for iron oxide NP growth, including rapidity, seedless growth, substrate compatibility, position selectivity, and patterning availability. Using its advantages, the LIHG process is used to fabricate flexible micro-supercapacitors based on laser-carbonized colorless polyimide films with iron oxide NPs.