Colorless to Multicolored, Fast Switching, and Highly Stable Electrochromic Devices Based on Thermally Cross-Linking Copolymer

Enhanced NIR Electrochromic Properties of Corannulene-(triphenylamine)5 and EDOT-Derived Polymers via Electrochemical Layer-by-Layer Polymerization Compared to Copolymerization

This study explores the electrochemical and electrochromic properties of polymers derived from corannulene-(triphenylamine)5 (CT) and 3,4-ethylenedioxythiophene (EDOT) through electrochemical copolymerization and layer-by-layer polymerization techniques. To address the high oxidation potential of EDOT, an EDOT dimer (BiEDOT) was synthesized, which facilitated successful copolymerization with CT. The resulting copolymer films, P10 and P8, exhibit enhanced near-infrared (NIR) electrochromic properties, with P8 showing better performance in NIR absorption. Comparative analysis with layer-by-layer films (PLs) reveals distinct electrochemical behaviors with PLs demonstrating higher NIR and lower visible absorbance with improved optical properties. Among PLs, PL6 exhibits the best NIR absorbance at 0.6 V, while the absorbance of the others does not show a significant increase until 0.7 V. Additionally, it also demonstrates excellent switching properties, with only a 3% loss of optical contrast at 1400 nm after 500 switching cycles. The study concluded that layer-by-layer polymerization offers an effective method for constructing PCT-PEDOT electrochromic films, providing better performance and higher NIR absorption than copolymerized films.

Highly transparent sustainable biogel electrolyte based on cellulose acetate for application in electrochemical devices

In this study, an easy and low-cost production method for a cellulose acetate-based gel polymer containing lithium perchlorate and propylene carbonate is described, as well as the investigation of its properties for potential use as an electrolyte in electrochemical devices. Cellulose acetate, a biopolymer derived from natural matrix, is colourless and transparent, as confirmed by the UV-Vis spectroscopy, with 85 % transparency in visible spectrum. The gels were prepared and tested at different concentrations and proportions to optimise their properties. Thermogravimetry, XRD, and FTIR analyses revealed crucial characteristics, including a substantial 90 % mass loss between 150 and 250 °C, a semi-crystalline nature with complete salt dissociation within the polymer matrix, and a decrease in intensity at 1780 cm-1 with increasing Li+ ion concentration, suggesting an improvement in ionic conduction capacity. In terms of electrochemical performance, the gel containing 10 % by mass of cellulose acetate and 1.4 M of LiClO4 emerged as the most promising. It exhibited a conductivity of 2.3 × 10-4 S.cm-1 at 25 °C and 3.0 × 10-4 S.cm-1 at 80 °C. Additionally, it demonstrated an ideal shape of cyclic voltammetry curves and stability after 400 cycles, establishing its suitability as an electrolyte in electrochemical devices.

Advanced inorganic nanomaterials for high-performance electrochromic applications

Electrochromic materials and devices with the capability of dynamic optical regulation have attracted considerable attention recently and have shown a variety of potential applications including energy-efficient smart windows, multicolor displays, atuto-diming mirrors, military camouflage, and adaptive thermal management due to the advantages of active control, wide wavelength modulation, and low energy consumption. However, its development still experiences a number of issues such as long response time and inadequate durability. Nanostructuring has demonstrated that it is an effective strategy to improve the electrochromic performance of the materials due to the increased reaction active sites and the reduced ion diffusion distance. Various advanced inorganic nanomaterials with high electrochromic performance have been developed recently, significantly contributing to the development of electrochromic applications. In this review, we systematically introduce and discuss the recent advances in advanced inorganic nanomaterials including zero-, one-, and two-dimensional materials for high-performance electrochromic applications. Finally, we outline the current major challenges and our perspectives for the future development of nanostructured electrochromic materials and applications.

Hydrogen-Bonding Induced Crosslinked Polymer Network for Highly Stable Electrochromic Device and a Construction Strategy for Black-Bilayer Electrochromic Film

This work presents a new strategy to achieve highly stable electrochromic devices and bilayer film construction. A novel solution-processable electrochromic polymer P1-Boc with quinacridone as the conjugated backbone and t-Boc as N-substituted non-conjugated solubilizing groups is designed. Thermal annealing of P1-Boc film results in the cleavage of t-Boc groups and the formation of N─H⋯O═C hydrogen-bonding crosslinked network, which changes its intrinsic solubility characteristics into a solvent-resistant P1 film. This film retains the electrochemical behavior and spectroelectrochemistry properties of the original P1-Boc film. Intriguingly, the electrochromic device based on the P1 film exhibits an ultrafast switching time (0.56/0.80 s at 523 nm) and robust electrochromic stability (retaining 88.4% of the initial optical contrast after 100 000 cycles). The observed cycle lifetime is one of the highest reported for all-organic electrochromic devices. In addition, a black-transparent bilayer electrochromic film P1/P2 is developed in which the use of the solvent-resistant P1 film as the bottom layer avoids interface erosion of the solution-processable polymer in a multilayer stacking.

Heteroacene-Based Polymer with Fast-Switching Visible-Near Infrared Electrochromic Behavior

The electrochromic properties and application of electronically conducting polymers (ECPs) (PTRPZ-EDOT) consisting of a 3,4-ethylenedioxythiophene (EDOT) and the heteroacene-based molecular scaffold, 6H-pyrrolo[3,2-b:4,5-b'] bis [1,4] benzothiazine (TRPZ), are reported. Known for its high electron mobility and conducting properties, the novel TRPZ scaffold was synthesized to possess two EDOT molecules termini affording TRPZ-EDOT. Electropolymerization of TRPZ-EDOT resulted in remarkable spectroscopic and conductive properties suitable for electrochromic device fabrication. Using atomic force microscopy (AFM), the average surface roughness and surface topography of PTRPZ-EDOT polymer thin films were determined. Spectroelectrochemical data showed that the polymer achieved switching times of 4.07 (coloration) and 0.47 s (bleaching) at 539 nm. The PTRPZ-EDOT film exhibits an optical contrast of 36-44% at 539 nm between its neutral and colored states, respectively. The NIR region from 1000 to 1700 nm shows the appearance of charge carrier bands with a 0-1 V potential range. An electrochromic device was successfully fabricated from PTRPZ-EDOT, showcasing the potential and applicability of the polymer material for advanced technologies such as smart windows, flexible electrochromic screens, and energy storage devices.

Large-fused-ring-based D-A type electrochromic polymer with magenta/yellowish green/cyan three-color transitions

Large-fused-ring-based conjugated polymers possess wide application prospects in optoelectronic devices due to their high charge transport and wide optical absorption. In this paper, three low-bandgap donor-acceptor (D-A) type polymers PBIT-X (X = 1, 2, 3) based on alkylated benzodithiophene and tris(thienothiophene) as donors and thiadiazol-quinoxaline as an acceptor were synthesized via Stille coupling polymerization at different (donor/acceptor) D/A molar feed ratios. The band gaps of PBIT-1, PBIT-2, PBIT-3 were 1.10 eV, 1.04 eV and 1.02 eV, respectively. Spectroelectrochemistry studies showed that the three D-A type polymers have dual bands located in visible and near-infrared regions in the neutral state. The three D-A type polymers possess good electrochromic properties, such as an optical contrast of 56% and response time of 0.3 s. In particular, PBIT-3 could achieve three color changes from magenta to yellowish green to cyan during the oxidation process. The results indicate that these D-A type conjugated polymers based on large fused-ring units exhibit multiple color changes, endowing them with huge potential applications in visible and near-infrared electrochromic devices.

Synthesis, Characterization, and Antibacterial Potential of Poly(o-anisidine)/BaSO4 Nanocomposites with Enhanced Electrical Conductivity

The poly(o-anisidine)/BaSO4 nanocomposites were prepared by oxidative polymerization of o-anisidine monomer with BaSO4 filler for the potential antibacterial properties of the composite materials. To achieve the optimal and tunable properties of the nanocomposites, the ratio of BaSO4 filler was changed at the rates of 1%, 3%, 5%, 7%, and 10% with respect to matrix. Different analytical techniques, i.e., FTIR and UV-visible spectroscopy, were employed for functional identification and optical absorption of the poly(o-anisidine)/BaSO4 nanocomposites. The FTIR data revealed the significant interaction between POA and BaSO4, as well as the good absorption behavior of the UV-visible spectra. The conducting properties were controllable by varying the load percentage of the BaSO4 filler. Furthermore, different bacterial strains, i.e., Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive), were used to evaluate the antibacterial activity of the POA/BaSO4 nanocomposites. The largest zones of inhibition 0.8 and 0.9 mm were reached using 7% and 10% for Staphylococcus aureus and Pseudomonas aeruginosa, respectively.

Self-healable PEDOT-based all-organic films with excellent electrochromic performances

PEDOT-based all-organic films after breaking up can be intrinsically self-healed through thermal stimulation (no more than 130 °C), and maintain excellent electrochromic properties.