Highly flexible and transparent film heater with electrospun copper conductive network via junction-free structure

•Flexible transparent film heaters are implemented using copper nanofiber network on a polymer film.•Copper nanostructures are formed on Pd catalytic nanofibers by electroless deposition.•Template of junction-free network was materialized through heat treatment.•High transmittance and conductivity due to long percolation path.•Durability of flexible transparent film heater verified under repeated external force.