Solution Processable and Patternable Poly(3,4-alkylenedioxythiophene)s for Large-Area Electrochromic Films Conductivity-controllable and photo-patternable conductive polythiophenes are prepared by solution-casting polymerization and applied to patterned electrochromic devices. A photofunctional group is introduced to thiophene derivatives for color tuning. This method and the resulting materials support the easy fabrication of electrochromic devices for large smart windows or flexible displays with designability and processability.