High-precision patterned electrochromic devices enabled by covalent photocrosslinking of disulfide side-chains

Electrochromic devices (ECDs) hold great promise for electronic tags and displays, yet their high-precision patterning remains challenging. Photocrosslinking technology in the field of electrochromics typically requires the addition of photoinitiators or crosslinkers, which often suffer from uneven distribution and limited patterning resolution. Here, we report a new photolithographic strategy wherein photosensitive disulfide bonds are directly incorporated into polymer side chains as intrinsic crosslinking sites, enabling direct UV patterning without external additives. This approach ensures uniform and controllable crosslinking at the molecular level, significantly enhancing the patterning resolution (≤5 μm) of conjugated polymer films for EC applications. Importantly, the disulfide incorporation does not affect the microstructure, electrochemistry, or EC performance of the material or film. The EC device based on the cross-linked ProDOT-SC film exhibits high contrast (70.0%), fast switching (coloration and bleaching both <3.5 s), high coloration efficiency (624 cm 2 /C), and outstanding stability. Overall, this study provides a photolithographic strategy based on side-chain modification, achieving high-precision patterning and excellent EC performance in laboratory-scale devices.