Phenylthiophene-Containing poly(2,5-dithienylpyrrole)s as potential anodic materials in high contrast and multicolored energy-saving electrochromic devices

Electrochromic energy-saving devices enhance indoor comfort and reduce building energy use. This study designs phenylthiophene-based poly(2,5-dithienylpyrrole)s as anodic polymer films with fast and uniform electrochromic transitions. The PDTTPP film changes from yellowish-green (neutral) to deep bluish violet (highly oxidized). The copolymer P(DTTPP-co-DTP) shows five distinct color states across voltages. ∆Tmax values reached 36.7% (PDTTPP, 970 nm), 63.5% (P(DTTPP-co-DTP), 1216 nm), and 46.2% (P(DTTPP-co-DTC), 932 nm). Coloration efficiencies were 303.84 cm² C⁻¹ and 260.65 cm² C⁻¹ for PDTTPP and P(DTTPP-co-DTP). Dual-type ECDs using these films showed high ∆Tmax and efficiency (e.g., 895.53 cm² C⁻¹ at 594 nm), with good cycling stability and memory.