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Correction for 'Effects of polymer precursor conjugation length on the optoelectronic properties of fluorinated benzothiadiazole-based D–A systems' by Daize Mo et al., New J. Chem., 2024, https://doi.org/10.1039/d4nj00131a. [ABSTRACT FROM AUTHOR]

Chlorination has proved to be an efficient method in tuning energy levels and optoelectronic properties of organic semiconducting materials with cheaper synthesis and low-cost raw materials when compared with the fluorinated analogues. Herein, in this work, 5-chlorobenzo[c][1,2,5]thiadizole (Cl-BT) unit was chosen as a new acceptor unit to design two new D-A type electrochromic conjugated polymer: P(Cl-T) and P(Cl-EDOT). The electrochemical behavior and electrochromic performances of above-mentioned chlorinated polymers were studied by electrochemical polymerization techniques and spectroelectrochemistry. Thanks to the strong electron-withdrawing ability of Cl-BT unit and the strong electron-donating properties of EDOT unit, the resultant Cl-EDOT precursor could electropolymerize into high quality hybrid polymer films at lower potential (0.71 V vs. Ag/AgCl) with favorable redox activity and better redox stability. Spectroelectrochemistry shown that as-formed lower band gaps P(Cl-EDOT) exhibits reversible color-changing nature from pale blue to gray accompanied with the moderate optical contrast (13.9%), fast response time (0.6 s), and favorable coloration efficiency (126.4 cm2 C−1) in the NIR region that was measured from the kinetic studies. By optimizing the tested electrolyte and solution, its electrochromic performance is further improved (optical contrast: 25.6%, response time: 0.25 s, coloration efficiency: 275.9 C−1 cm2). The favorable redox stability and electrochromic performance of P(Cl-EDOT) make it a good candidate to construct electrochromic device, and Cl-BT unit should be a promising building block in designing high performance near infrared electrochromic materials. [Display omitted] • Two electrochromic precursor based on 5-chlorobenzo[c][1,2,5]thiadizole unit were synthesized by Stille coupling reaction. • Different donor brings different influence on the photophysical properties of the chlorinated precursors and its polymers. • The introduction of EDOT unit is beneficial for the preparation of better-quality chlorinated polymers. • P(Cl-EDOT) exhibit better redox activity and stability, and satisfied electrochromic performances. • Chlorinated benzothiadiazole could be a promising building blocks in constructing high performance D-A conjugated polymers. [ABSTRACT FROM AUTHOR]

In this paper, two novel D-A-D type molecules (EBZFO1 and TBZFO2), which consisting of 7 H-benzo[ c ]fluoren-7-one as electron acceptor (A) unit, 3,4-ethylenedioxythiophene (EDOT) and thiophene (Th) as the terminal donor (D) units, were designed and synthesized. Afterwards, the corresponding D-A polymers of P(EBZFO1) and P(TBZFO2) were prepared by electrochemical deposition method. The electrochemical behavior of the monomers, electrochemical, and electrochromic properties of the D-A polymers were comparatively studied. Although both of the monomers have lower onset oxidation potentials (1.0 V/1.2 V) and good adherence on the electrode, the redox stability of their polymers was very different. P(EBZFO1) displayed much better redox stability (remaining 78.4 % electroactivity after 1000 cycles), good optical stability (2 % reduction in optical contrast after 1500 s), and stable optical memory, while P(TBZFO2) remained inferior redox stability with only 8.82 % of its original electroactivity was retained after 1000 cycles. As a result, higher optical band gap of P(TBZFO2) (1.65 eV) displayed much worse electrochromic performances with the normal optical contrast (11.4 %∼46 %) and relatively slow switching time (2.5–3.8 s). By contrast, P(EBZFO1) (band gap: 1.55 eV) showed favorable optical contrast (15.8 %) at 1100 nm with a very fast response time of 0.24 s, and decent coloration efficiency (228.8 cm2 C−1 at 433 nm). From these results, P(EBZFO1) can further render an appropriate electrochromic material for the smart windows or displays. [Display omitted] • Two fluorenone derivative acceptor units-based D-A type polymer precursors were synthesized. • Different donor units caused outstanding effects on the photophysical properties of the precursors and its polymers. • EBZFO1 and P(EBZFO1) exhibited much lower onset oxidation potentials. • Lower band gap P(EBZFO1) shown favorable redox activity and better redox stability. • P(EBZFO1) has high coloration efficiency, short response time, and good optical memory behavior. [ABSTRACT FROM AUTHOR]