N-(thiophen-2-ylmethylene)aniline- and N-(thiazol-2-ylmethylene)aniline-containing poly(2,5-dithienylpyrrole)s as anodically coloring polymers for high contrast electrochromic devices

Abstract

Two N-(thiophen-2-ylmethylene)aniline- and N-(thiazol-2-ylmethylene)aniline-containing poly(dithienylpyrrole)s (PTA and PZA) are deposited on indium tin oxide (ITO) glass substrates and their electrochemical, spectral, and electrochromic performances are characterized. PTA and PZA display reversible multicolor chromism in the UV–Vis–NIR region. PTA is ocher, olive, slate grey, and bluish-grey at −0.2, 0.8, 1.0, and 1.2 V, respectively, whereas PZA is terreous, coffee, grey, and deep grey at −0.2, 0.2, 1.0, and 1.4 V, respectively. Kinetic investigations of polymeric films display the transmittance change (ΔΤ) of PTA and PZA between the doped and undoped state is 35.4% at 1286 nm and 31.2% at 1218 nm, respectively. PZA attains a high coloration efficiency (η = 218.8 cm2 C−1 at 1218 nm) in a liquid solution. Bilayer electrochromic devices (ECDs) based on PTA (or PZA) as anodic polymer and PProDOTEt2 (or PProDOTBz2) as cathodic polymer were fabricated. The ΔT of PTA/PProDOTBz2 and PZA/PProDOTBz2 ECDs between the bleached and colored state is 70.2% at 622 nm and 64.7% at 622 nm, respectively. Moreover, four ECDs display short response time and multichromic reversible redox behaviors, indicating that PTA and PZA are promising candidates for future electrochromic and optoelectronic applications.