Synthesis and multi-electrochromic properties of asymmetric structure polymers based on carbazole-EDOT and 2, 5–dithienylpyrrole derivatives

Effects of Phenoxazine Chromophore on Optical, Electrochemical and Electrochromic Behaviors of Carbazole-Thiophene Derivatives

Phenoxazine, as an organic-small-molecule chromophore, has attracted much attention for its potential electrochromic applications recently. To develop appealing materials, phenoxazine chromophores were introduced at the N-position of carbazole-thiophene pigment, yielding two novel monomers (DTCP and DDCP), whose chemical structures were characterized by NMR, HRMS and FTIR. The results of the optical property study indicate that little influence could be observed in the presence of the phenoxazine chromophore. Corresponding polymer films on the surface of an ITO/glass electrode were obtained through electropolymerization. The electrochemical features displayed were various due to the introduction of the phenoxazine group. The spectroelectrochemical results demonstrate that the color of the polymer films could be changed. Compared with the PDDC films, the PDDCP films exhibited three different colors (tangerine, green and purple colors) in different redox states, which could be attributed to the synergistic effect between the carbazole-thiophene conjugate chain and the phenoxazine group. Moreover, fast switching time could be seen due to the presence of the phenoxazine chromophore. This study could provide a reference for obtaining high-performance electrochromic materials.

A Soluble ProDOT-Based Polymer and Its Electrochromic Device with Yellow-to-Green Color Switching Towards Camouflage Application

Yellow-to-green electrochromic color switching plays a key role in the intelligent adaptive camouflage under the visible light environment in future military camouflage applications. Here, we designed and synthesized a soluble electrochromic conjugated pDPTD polymer, mainly based on perylo[1,12-bcd]thiophene and the novel ProDOT groups. The pDPTD polymer displayed a yellow-to-green electrochromism with large optical contrast and fast switching times. Based on the pDPTD polymer film, a yellow-to-green electrochromic device was achieved, showing an orange-yellow color at -0.4 V with L*a*b* color coordinates of 88.5, 18.5, and 34.2 and a pale green color at 0.7 V with L*a*b* color coordinates of 85.6, -4.8, and 11.5, together with a large optical contrast of 43.5% and fast switching times of 2.4/3.2 s. These results indicated that the pDPTD polymer could serve as a potential electrochromic material for yellow/green system camouflage applications.

Electropolymerization processing of side-chain engineered EDOT for high performance microelectrode arrays

Microelectrode Arrays (MEAs) are popular tools for in vitro extracellular recording. They are often optimized by surface engineering to improve affinity with neurons and guarantee higher recording quality and stability. Recently, PEDOT:PSS has been used to coat microelectrodes due to its good biocompatibility and low impedance, which enhances neural coupling. Herein, we investigate on electro-co-polymerization of EDOT with its triglymated derivative to control valence between monomer units and hydrophilic functions on a conducting polymer. Molecular packing, cation complexation, dopant stoichiometry are governed by the glycolation degree of the electro-active coating of the microelectrodes. Optimal monomer ratio allows fine-tuning the material hydrophilicity and biocompatibility without compromising the electrochemical impedance of microelectrodes nor their stability while interfaced with a neural cell culture. After incubation, sensing readout on the modified electrodes shows higher performances with respect to unmodified electropolymerized PEDOT, with higher signal-to-noise ratio (SNR) and higher spike counts on the same neural culture. Reported SNR values are superior to that of state-of-the-art PEDOT microelectrodes and close to that of state-of-the-art 3D microelectrodes, with a reduced fabrication complexity. Thanks to this versatile technique and its impact on the surface chemistry of the microelectrode, we show that electro-co-polymerization trades with many-compound properties to easily gather them into single macromolecular structures. Applied on sensor arrays, it holds great potential for the customization of neurosensors to adapt to environmental boundaries and to optimize extracted sensing features.

Conjugated Polymers Containing EDOT Units as Novel Materials for Electrochromic and Resistance Memory Devices

Four new multifunctional polymers (P1, P2, P3, and P4) containing EDOT units were synthesized by the Stille coupling reaction. A PL spectrum test found that the introduction of large conjugated groups led to strong fluorescence emission in all polymers. Among the electrochromic and switch properties, these polymer films exhibited reversible color changes, as well as good coloring efficiency. Electrochemical experiments found that the initial oxidation potentials of the polymers were 1.27 V, 1.67 V, 1.78 V, and 1.58 V, respectively. Among them, P3 showed a higher coloring efficiency (283.3 cm²·C^-1), and P2 showed a shorter response time (t_c = 2.2 s, t_b = 2.8 s). These polymers all exhibited electrochromic and resistive switching storage characteristics. They have good solubility in many organic solvents. In the resistance switch memory characteristics, all polymers had obvious memristive properties, and P4 exhibited a larger switch current ratio (2527.42) and a smaller threshold voltage (0.9 V).

Polypyrrole derivatives for optoelectronic applications: a DFT study on the influence of side groups

Conjugated organic polymers have been considered interesting materials for various technological applications, mainly due to their unique optoelectronic properties and the variety of methods employed in their synthesis. In this context, polypyrrole (PPy) derivatives have been widely employed. The great versatility of synthesis of this material allows the production of a number of derivatives with distinct properties, allowing their application in several areas. In this report, aiming to guide the design of compounds with specific features, electronic structure calculations were conducted to evaluate the influence of side groups in the structural, optical and electronic properties of PPy derivatives. The calculations were carried out for oligomeric systems in the framework of density functional theory. Preliminary benchmark studies were conducted by employing two distinct functionals for geometry optimization and evaluation of optoelectronic properties. Comparative studies of the bond length alternation, spatial and energetic distribution of the frontier orbitals, electronic gaps, exciton binding energies, optical absorption spectra and electronic density of states were conducted for each derivative and the influence of the side groups was discussed in terms of their electron donation/withdrawing properties. A set of simple rules (linear equations) was proposed for the prediction of optoelectronic properties of PPy derivatives. In particular, the results have shown that simple Hammett parameters of side groups are sufficient to enable the design of improved materials.