Ultrafast ambipolar switching in electrochromic copolymer thin films of zinc(ii) tetrakis(4-aminophenyl)porphyrin-3,4-ethylenedioxythiophene




Kochrekar, Sachin; Sappati, Subrahmanyam; Kumar Jha, Plawan; Mäkilä, Ermei; Jadhav, Ashwini; Damlin, Pia; Salomäki, Mikko; Kvarnström, Carita

PublisherRoyal Society of Chemistry

2025

 Journal of Materials Chemistry. C

2050-7526

2050-7534

DOIhttps://doi.org/10.1039/d5tc03045e

https://doi.org/10.1039/d5tc03045e

https://research.utu.fi/converis/portal/detail/Publication/505459208



Electrocopolymerization of different monomers is a useful approach for developing materials with tailored electrochromic properties and expanded color palettes. We report electrocopolymerization of two distinct monomers – zinc(II) tetrakis(4-aminophenyl)porphyrin (ZnTAPP) and 3,4-ethylenedioxythiophene (EDOT) on an FTO-coated glass substrate. Our copolymer, poly(ZnTAPP–EDOT), exhibits a reversible color change from orange-brown to olive-green, with optical contrasts of 25% and 31% in the visible and beginning of the near-IR (bNIR) regions, respectively. It also demonstrates high coloration efficiencies of 434 cm2 C−1 (visible region) and 181 cm2 C−1 (bNIR region). Furthermore, poly(ZnTAPP–EDOT) retains 88%of its electrochromic performance in the visible and 82% in the bNIR regions after 200 redox cycles, along with a fast switching response and strong optical memory under open-circuit conditions. Our time-dependent density functional theory (TDDFT) calculations reveal that the increasing EDOT units between ZnTAPP moieties promote a systematic redshift in absorption peaks and enhance oscillator strengths, attributed to extended π-delocalization facilitated by the added EDOT linkages, corroborating experimental UV-vis data. Our results suggest that the electrocopolymerization of suitable porphyrins with selective monomers can produce electrochromic materials with tunable optical properties, high efficiency, and stability, making them well-suited for use in electrochromic devices.


The author acknowledges Neste and Fortum, and Real Estate Foundation Turku for financial support. SS expresses gratitude to the Gdańsk University of Technology for their support under the “Excellence Initiative Research University (IUDB)” program (Grant no. 28/1/2025/DUB/IV.2a/Eu).


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