Synthesis and electrochemical capacitive performance of thieno[3,4-b]pyrazine-based Donor-Acceptor type copolymers used as supercapacitor electrode material

Fluoridation of D-A Ambipolar Polymers to Accelerate Ion Migration toward High-Performance Symmetric Dual-Ion Energy Storage Devices

Dual-ion electrochemical energy storage devices have attracted much attention due to their cost effectiveness and high operating voltage. Electrochemical properties such as the specific capacity of dual-ion energy storage devices are closely related to ion migration. However, the ion migration of dual-ion energy storage devices is slow, especially the cation migration, resulting in limited discharge capacity and poor rate performance. In this study, fluorinated and nonfluorinated ambipolar conductive polymers were prepared as electrode materials. The effects of fluorination on aggregation and solvent were studied as well as its role in improving ion migration. The results show that fluorination can increase the force of fluorination on the solvent, reduce the level of binding of the solvent to the ion, and regulate the aggregation state. Compared with the unfluorinated polymer of PEPOPE, the ion migration and electrochemical kinetics of PEPFEP were significantly improved, and the PEPFPE (71 F/cm3) has a higher negative specific capacity than PEPOPE (24 F/cm3) at a current density of 5 A/cm3.

Synthesis and Spectroscopic Characterization of Thienopyrazine-Based Fluorophores for Application in Luminescent Solar Concentrators (LSCs)

Organic fluorophores have found broad application as emitters in luminescent solar concentrators (LSCs) for silicon photovoltaics. In particular, the preparation of organic conjugated systems with intense light-harvesting ability, emissions in the deep-red and NIR regions, and large Stokes shift values represent a very challenging undertaking. Here, we report a simple and easy way to prepare three symmetrical donor–acceptor–donor (DAD) organic-emitting materials based on a thienopyrazine core. The central core in the three dyes was modified with the introduction of aromatic substituents, aiming to affect their optical properties. The fluorophores were characterized by spectroscopic studies. In all cases, visible-NIR emissions with large Stokes shifts were found, highlighting these molecules as promising materials for the application in LSCs.

Thiophene-Based Trimers and Their Bioapplications: An Overview

Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art.

Donor-Acceptor-Donor Copolymers with 3,4-Ethylenedioxythiophene Moiety: Electropolymerization and Effect on Optoelectronic and Electrochromic Properties

Three random copolymers PE- co -M1, PE- co -M2, and PE- co -M3 were obtained by electrochemical polymerization of donor-acceptor-donor monomers M1, M2, and M3 with 3,4-ethylenedioxythiophene moiety, respectively, using a 1:1 molar ratio of the corresponding monomers, to find new properties and a more effective way to control the optoelectronic properties in conjugated system. For comparison purpose, polymers P1, P2, and P3 were prepared from the corresponding monomer units M1-M3, respectively, by electrochemical polymerization. We also present efficient synthesis, characterization, and comparative density functional theory (DFT) calculations of the monomers M1-M3 and polymers P1-P3. Cyclic voltammetry, spectroelectrochemistry, and electrochromic properties of all of the polymers P1-P3 and copolymers PE- co -M1, PE- co -M2, and PE- co -M3 were carried out and a throughout comparison was made. We have shown that electrochemical copolymerization is a powerful strategy to tune the highest occupied molecular orbital energy level, band gap, and color of the copolymer. Thus, this finding clearly indicates that the copolymers show significantly different optoelectronic properties compared to their constituent polymers.

High-Performance Asymmetric Electrochromic-Supercapacitor Device Based on Poly(indole-6-carboxylicacid)/TiO2 Nanocomposites

A difunctional porous network of poly(indole-6-carboxylicacid) (PICA)/TiO₂ nanocomposites is first prepared using TiO₂ nanorod arrays as the scaffold. Because of the synergistic effect of PICA and TiO₂, the nanocomposites show good electrochemical performance, a high specific capacitance value (23.34 mF cm^-2), and excellent galvanostatic charge-discharge stability. Meanwhile, this nanocomposite can be reversibly switched (yellow, green, brown) with a high coloration efficiency (124 cm² C^-1). An asymmetric electrochromic-supercapacitor device (ESD) is also constructed using the PICA/TiO₂ nanocomposites as the anode material and poly(3,4-ethylenedioxythiophene) as the cathode material. This ESD has robust cycle stability and a high specific capacitance value (9.65 mF cm^-2), which can be switched from light green to dark blue. After charging, the device can light up a single LED for 108 s, and the energy storage level can also be monitored by the corresponding color changes. This constructed ESD will have great potential applications in intelligent energy storage and other smart electronic fields.

Effects of Pyrazine Derivatives and Substituted Positions on the Photoelectric Properties and Electromemory Performance of D⁻A⁻D Series Compounds

Pyrazine derivatives quinoxaline and pyridopyrazine were selected as the acceptors, and benzocarbazole was used as the donor to synthesize four different D⁻A⁻D compounds. The results showed that 2,3-bis(decyloxy)pyridine[3,4-b]pyrazine (DPP) exhibited stronger electron-withdrawing ability than that of 2,3-bis(decyloxy)quinoxaline (DPx), because DPP possesses one more nitrogen (N) atom, resulting in a red-shift of the intramolecular charge transfer (ICT) absorption bands and fluorescent emission spectra for compounds with DPP as the acceptor compared with those that use DPx as the acceptor. The band-gap energy (Eg) of the four D⁻A⁻D compounds were 2.82 eV, 2.70 eV, 2.48 eV, and 2.62 eV, respectively, for BPC-2DPx, BPC-3DPx, BPC-2DPP, and BPC-3DPP. The solvatochromic effect was insignificant when the four compounds were in the ground state, which became significant in an excited state. With increasing solvent polarity, a 30⁻43 nm red shift was observed in the emissive spectra of the compounds. The thermal decomposition temperatures of the four compounds between 436 and 453 °C had very high thermal stability. Resistor-type memory devices based on BPC-2DPx and BPC-2DPP were fabricated in a simple sandwich configuration, Al/BPC-2DPx/ITO or Al/BPC-2DPP/ITO. The two devices showed a binary non-volatile flash memory, with lower threshold voltages and better repeatability.

The NiGa-LDH@NiWO4 nanocomposite as an electrode material for pseudocapacitors

NiGa-LDH@X-NiWO₄ (X: 3, 5 or 10 wt% NiWO₄) nanocomposites were prepared at room temperature under mild conditions.

The Availability of Neutral Cyan, Green, Blue and Purple Colors from Simple D⁻A Type Polymers with Commercially Available Thiophene Derivatives as the Donor Units

In this paper, the Stille coupling reaction was used to prepare four donor⁻acceptor⁻donor (D⁻A⁻D) type monomers. For this purpose, 2,3-bis(4-methoxyphenyl) quinoxaline was used as the acceptor unit, and thiophene derivatives (3,4-ethylenedioxythiophene, or EDOT; 3-methoxythiophene, or MOTh; 3-methylthiophene, or MTh; and thiophene, or Th) were used as the donor units. The monomers were polymerized to the corresponding polymers by the cyclic voltammetry (CV) or potentiostatic method. The band gaps and the adsorption profiles of the polymers were finely tuned with the incorporation of the different thiophene units. All four polymers have low band gaps, and switched between the colored neutral states and the highly transmissive oxidized state. We were successfully able to obtain the valuable neutral colors of cyan, green, blue, and violet for the polymers employing EDOT, MOTh, MTh, and Th as the donor unit, respectively. Furthermore, electrochromic kinetic investigations showed that all four polymers displayed excellent optical contrasts (ΔT%), fast switching times, high coloration efficiencies, and robust stabilities, indicating that these four polymers are probably promising choices for developing electrochromic devices.

Synthesis, Characterization and Application of Four Novel Electrochromic Materials Employing Nitrotriphenylamine Unit as the Acceptor and Different Thiophene Derivatives as the Donor

In this study, four novel donor⁻acceptor systems, 4-(2,3-dihydrothieno[3,4-b][1,4]dioxin -5-yl)-N-(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)phenyl)-N-(4-nitrophenyl)aniline (NETPA), 4- (4-methoxythiophen-2-yl)-N-(4-(4-methoxythiophen-2-yl)phenyl)-N-(4-nitrophenyl)aniline (NMOTPA), 4-(4-methylthiophen-2-yl)-N-(4-(4-methylthiophen-2-yl)phenyl)-N-(4-nitrophenyl) aniline (NMTPA) and 4-nitro-N,N-bis(4-(thiophen-2-yl)phenyl)aniline (NTTPA), were successfully synthesized by Stille coupling reaction and electropolymerized to obtain highly stable conducting polymers, PNETPA, PNMOTPA, PNMTPA and PNTTPA, respectively. The polymers were characterized using cyclic voltammetry (CV), step profiling and UV⁻Vis⁻NIR spectroscopy. The band gaps (Eg values) were 1.34, 1.59, 2.26, and 2.34 eV, for PNETPA, PNMOTPA, PNMTPA and PNTTPA, respectively. In addition, electrochromic switching showed that all polymers exhibit outstanding optical contrasts, high coloration efficiencies and fast switching speeds in the near-infrared region (NIR). These properties make the polymers suitable materials for electrochromic applications in NIR region.