Poly(3,4-ethylenedioxyselenophene): effect of solvent and electrolyte on electrodeposition, optoelectronic and electrochromic properties

In Situ Electropolymerized Ambipolar Copolymers for Vertical OECTs

A novel approach is reported for obtaining ambipolar electroactive polymers via in situ electropolymerization for vertical organic electrochemical transistor (vOECT) applications. It is shown that electropolymerization is a practical and efficient method to obtain copolymers without contamination from chemical polymerization processes. To this end, two monomers, G-DTP-Bu-NDI and G-DTP-G-NDI, are proposed, comprising naphthalene diimide (NDI) as the acceptor core and dithienopyrrole (DTP) as the donor unit, capable of forming carbon-carbon bonds under the influence of an electric current. The incorporation of oligo(oxyethylene) (OEG) side groups ensures their amphiphilicity. Both compounds underwent successful electrochemical polymerization, resulting in thin, porous, uniform polymer layers on the electrode surface. The synthesized polymers are further examined using electrochemical and spectroelectrochemical techniques in both organic and aqueous electrolytes. Regardless of the electrolyte medium (aqueous or non-aqueous), poly(G-DTP-Bu-NDI), and poly(G-DTP-G-NDI) exhibit stable electroactivity, as demonstrated by numerous scans showing ambipolar redox behavior. Both polymers are tested as components of vertical OECTs, following in situ electrochemical deposition within a 350 nm channel. The recorded transfer characteristics suggest that the fabricated donor-acceptor (D-A) compounds hold promise for developing a new generation of ambipolar ECT devices.

From Traditional to Novel Printed Electrochromic Devices: Material, Structure and Device

Electrochromic materials have been considered as a new way to achieve energy savings in the building sector due to their potential applications in smart windows, cars, aircrafts, etc. However, the high cost of manufacturing ECDs using the conventional manufacturing methods has limited its commercialization. It is the advantages of low cost as well as resource saving, green environment protection, flexibility and large area production that make printing electronic technology fit for manufacturing electrochromic devices. This paper reviews the progress of research on printed electrochromic devices (ECDs), detailing the preparation of ECDs by screen printing, inkjet printing and 3D printing, using the scientific properties of discrete definition printing method. Up to now, screen printing holds the largest share in the electrochromic industry due to its low cost and large ink output nature, which makes it suitable especially for printing on large surfaces. Though inkjet printing has the advantages of high precision and the highest coloration efficiency (CE) can be up to 542 ± 10 cm²C^-1, it has developed smoothly, and has not shown rigid needs. Inkjet printing is suitable for the personalized printing production of high precision and small batch electronic devices. Since 3D printing is a new manufacturing technology in the 21st century, with the characteristics of integrated molding and being highly controllable, which make it suitable for customized printing of complex devices, such as all kinds of sensors, it has gained increasing attention in the past decade. Finally, the possibility of combining screen printing with inkjet printing to produce high performance ECDs is discussed.

A review of π-conjugated polymer-based nanocomposites for metal-ion batteries and supercapacitors

Owing to their extraordinary properties of π-conjugated polymers (π-CPs), such as light weight, structural versatility, ease of synthesis and environmentally friendly nature, they have attracted considerable attention as electrode material for metal-ion batteries (MIBs) and supercapacitors (SCPs). Recently, researchers have focused on developing nanostructured π-CPs and their composites with metal oxides and carbon-based materials to enhance the energy density and capacitive performance of MIBs and SCPs. Also, the researchers recently demonstrated various novel strategies to combine high electrical conductivity and high redox activity of different π-CPs. To reflect this fact, the present review investigates the current advancements in the synthesis of nanostructured π-CPs and their composites. Further, this review explores the recent development in different methods for the fabrication and design of π-CPs electrodes for MIBs and SCPs. In review, finally, the future prospects and challenges of π-CPs as an electrode materials for strategies for MIBs and SCPs are also presented.

Nanostructured PEDOT Coatings for Electrode-Neuron Integration

Neural electrodes have been developed for the diagnosis and treatment of stroke, sensory deficits, and neurological disorders based on the electrical stimulation of nerve tissue and recording of neural electrical activity. A low interface impedance and large active surface area for charge transfer and intimate contact between neurons and the electrode are critical to obtain high-quality neural signal and effective stimulation without causing damage to both tissue and electrode. In this study, a nanostructured poly(3,4-ethylenedioxythiophene) (PEDOT) coating with lots of long protrusions was created via a one-step electrochemical polymerization from a dichloromethane solution without any rigid or soft templates. The nanostructures on the PEDOT coating were basically formed by intertwined PEDOT nanofibers, which further enhanced the active surface area. The fuzzy PEDOT-modified microelectrodes exhibited an impedance as low as 1 kΩ at 1 kHz, which is much lower than those produced from aqueous 3,4-ethylenedioxythiophene (EDOT) solution, and it was comparable with PEDOT films or composites created from/with template materials. Also, more than 150 times larger charge storage capacity density was obtained compared to the unmodified microelectrode. An in vitro biocompatibility test performed on PC12 cells and primary cells suggested that the PEDOT coatings support cell adhesion, growth, and neurite extension. These results suggest the great potential of the nanostructured PEDOT coating as an electroactive and biosafe intimate contact between the implanted neural electrode and neurons.

Oxidative MLD of Conductive PEDOT Thin Films with EDOT and ReCl5 as Precursors

Because of its high conductivity and intrinsic stability, poly(3,4-ethylenedioxythiophene (PEDOT) has gained great attention both in academic research and industry over the years. In this study, we used the oxidative molecular layer deposition (oMLD) technique to deposit PEDOT from 3,4-ethylenedioxythiophene (EDOT) and a new inorganic oxidizing agent, rhenium pentachloride (ReCl5). We extensively characterized the properties of the films by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Raman, and conductivity measurements. The oMLD of polymers is based on the sequential adsorption of the monomer and its oxidation-induced polymerization. However, oMLD has been scarcely used because of the challenge of finding a suitable combination of volatile, reactive, and stable organic monomers applicable at high temperatures. ReCl5 showed promising properties in oMLD because it has high thermal stability and high oxidizing ability for EDOT. PEDOT films were deposited at temperatures of 125-200 °C. EDS and XPS measurements showed that the as-deposited films contained residues of rhenium and chlorine, which could be removed by rinsing the films with deionized water. The polymer films were transparent in the visible region and showed relatively high electrical conductivities within the 2-2000 S cm-1 range.

The effect of electrolytes on the electrochromic performance of nickel-substituted tungstophosphate and TiO2 nanowire composite films

A film based on POM and TiO₂ nanowires in Li⁺-based media displays enhanced electrochromic performance compared to that in H⁺-based electrolyte.

Experimental review of PEI electrodeposition onto copper substrates for insulation of complex geometries

Polyetherimide (PEI) was used for coating copper substrates via electrophoretic deposition (EPD) for electrical insulation. Different substrate preparation and electrical field application techniques were compared, demonstrating that the use of a pulsed voltage of 20 V allowed for the best formation of insulating coatings in the 2–6 μm thickness range. The results indicate that pulsed EPD is the best technique to effectively coat conductive substrates with superior surface finish coatings that could pass a dielectric withstand test at 10 kV mm⁻¹, which is of importance within the EV automotive industry.

Electrophoretic deposition relying on electrodeposition of charged polymers via modulated electrical fields is reported. Superior surface finishes that could pass a dielectric withstand test at 10 kV mm⁻¹ were obtained for pulsed potentials at 20 V.

Benzothiadiazole bridged EDOT based donor-acceptor polymers with tunable optical, electrochemical, morphological and electrochromic performance: effects of solvents and electrolytes

Donor-acceptor (D-A) polymers have been widely studied for their tunable electronic properties, however, it is surprising that systematic studies on the effect of different solvents and electrolytes on their opto-electrochemical, morphological and electrochromic performance have drawn only little attention. In the presented work, nine different D-A polymer films, poly(4,7-di(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)benzo[1,2,5]thiadiazole) (a-i-P1), were electrosynthesised using different polar solvents (PC, MeCN and DCM) and supporting electrolytes (TBAPF6, TBAClO4 and TBABF4). A thorough study of these D-A polymer films using cyclic voltammetry, UV-Vis-NIR spectroscopy, FE-SEM, spectroelectrochemistry and electrochromic techniques has been performed. We found a significant effect of both the supporting electrolytes and solvents on the morphology of polymer films which correlates well with their opto-electronic properties. Films prepared using the TBAClO4/PC system show a smooth morphology with a significantly high coloration efficiency of 264 cm2 C-1 and an optical contrast of 65.3%. Such differences in the optical and electrochemical properties of polymer films were explained by the ion pair formation during polymerisation.

Recent advances in poly(3,4-ethylenedioxyselenophene) and related polymers

This review highlights the recent progress in synthesis, properties, applications and future outlook of PEDOS based conjugated polymers.

Effects on the photovoltaic properties of copolymers with five-membered chalcogen-π-heterocycle bridges

Polymers containing different chalcogen-π-heterocycles in their conjugated backbones present varied photovoltaic characteristics, and the PBDB-TF-S:BTP-4Cl-based OSCs present a desirable PCE of 16.22%.