A Printable Flexible and Transparent Heater Applicable to Arbitrary Surfaces, Fabricable by the Soft-Contact Micropatterning of an Ionic Metal Solution

We demonstrate the facile fabrication of flexible and transparent heating structures via the soft-contact printing and patterning (SCOP) of an ionic metal solution layer, a process generally applicable to flat, flexible, and curved surfaces with scalable sizes. The SCOP process involves the conformal contact of a soft micropattern mold onto an ionic metal solution and mild thermal annealing under controlled temperature and pressure conditions to reduce metal ions into a micropatterned metallic structure. Through parametric optimization of the SCOP pressure and annealing temperature, multilayering with sequential SCOP processes, and airbrush coating of a carbon nanotube solution, a printable metallic micropattern can be tailored to a high-performance transparent heater capable of achieving the temperature up to ~ 125 °C at 8 V and optical transmittance of 80% (achievable > 250 °C at 5 V when multilayered and CNT-reinforced). The scalability and solution processability of the developed process pave the way for the high-throughput eco-friendly fabrication of flexible and transparent heaters on arbitrary surfaces as well as many practical devices, including but not limited to printable electronic and photonic components and wearable sensors as well as warm-up gear.