On-Chip Direct Laser Writing of PAN-Based Carbon Supercapacitor Electrodes.

The carbonization of polyacrylonitrile (PAN) by direct laser writing to produce microsupercapacitors directly on-chip is reported. The process is demonstrated by producing interdigitated carbon finger electrodes directly on a printed circuit board (PCB), which is then employed to characterize the supercapacitor electrodes. By varying the laser power, the process can be tuned from carbonization to material ablation. This allows to not only convert pristine PAN films into carbon electrodes, but also to pattern and cut away non-carbonized material to produce completely freestanding carbon electrodes. While the carbon electrodes adhere well to the printed circuit board, non-carbonized PAN is peeled off the substrate. Specific capacities as high as 260 µF cm⁻2 are achieved in a supercapacitor with 16 fingers.