Vapor Phase Polymerized Poly Research Articles

Effects of Secondary Dopant Anions on Emissivity and Related Properties of Poly(3,4-ethylenedioxythiophene).

Smart materials that are energy efficient and take up less space are crucial in the development of new technologies. Electrochromic polymers (ECPs) are one such class of materials that actively change their optical behavior in both visible and infrared parts of the electromagnetic spectrum. They show promise in a wide range of applications, from active camouflage to smart displays/windows. The full capabilities of ECPs are still yet to be explored, for while their electrochromic properties are well established, their IR modulation is less reported on. This study addresses the potential of ECPs in active IR modulating devices by optimization of Vapor Phase Polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) thin films via the substitution of its dopant anion. Dynamic ranges denoting emissivity changes between reduced and oxidized states of PEDOT were found across dopants of tosylate, bromide, sulfate, chloride, perchlorate and nitrate. Relative to the emissivity of reduced (neutral) PEDOT, a range of ±15% was achieved from the doped PEDOT films, and a maximum dynamic range of 0.11 across a 34% change was recorded for PEDOT doped with perchlorate. This article is protected by copyright. All rights reserved.

Influence of Postsynthesis Heat Treatment on Vapor-Phase-Polymerized Conductive Polymers.

The effect of thermal treatment on the structure and electrical/optical properties of vapor phase-polymerized poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:Tos) and polypyrrole:tosylate (PPy:Tos) polymer films was investigated. Thermal treatment was applied postpolymerization but prior to washing the embedded oxidant layer out of the polymer film. Structural and chemical changes arising from the treatment were studied in the context of their conductive and electrochromic behavior. Spectroscopic analysis indicated a rise in the doping levels of both conductive polymers when exposed to thermal treatment. Additionally, an increase in the film thickness was recorded after the oxidant and other unbound species were removed from the polymer layer using an ethanol rinse. As such, a strong indication that polymerization continued even in the absence of (external) monomer vapor was present. This film thickness increase was most pronounced for PPy:Tos but also present in the PEDOT:Tos film. Heat-treated films exhibited enhanced cohesion, making them more robust and therefore increasing the viability for the material to be used in the optoelectronics area. This robustness, due to additional (cross-linking) oligomer growth, came at the expense of lower conductivity relative to their untreated counterparts.

All-Organic High-Performance Piezoelectric Nanogenerator with Multilayer Assembled Electrospun Nanofiber Mats for Self-Powered Multifunctional Sensors

Rapid development of wearable electronics, piezoelectric nanogenerator (PNG), has been paid a special attention because of its sustainable and accessible energy generation. In this context, we present a simple yet highly efficient design strategy to enhance the output performance of an all-organic PNG (OPNG) based on multilayer assembled electrospun poly(vinylidene fluoride) (PVDF) nanofiber (NF) mats where vapor-phase polymerized poly(3,4-ethylenedioxythiophene)-coated PVDF NFs are assembled as electrodes and neat PVDF NFs are utilized as an active component. In addition to the multilayer assembly, electrode compatibility and durability remain a challenging task to mitigate the primary requirements of wearable electronics. A multilayer networked three-dimensional structure integrated with a compatible electrode thereby provides enhanced output voltage and current (e.g., open-circuit voltage, Voc ≈ 48 V, and short-circuit current, Isc ≈ 6 μA, upon 8.3 kPa of the applied stress amplitude) with superior piezoelectric energy conversion efficiency of 66% compared to the single-mat device. Besides, OPNG also shows ultrasensitivity toward human movements such as foot strikes and walking. The weight measurement mapping is critically explored by principal component analysis that may have enormous applications in medical diagnosis to smart packaging industries. More importantly, fatigue test under continuous mechanical impact (over 6 months) shows great promise as a robust wearable mechanical energy harvester.

Vapor-phase polymerized poly(3,4-ethylenedioxythiophene) (PEDOT)/TiO2 composite fibers as electrode materials for supercapacitors

Vapor-phase polymerized poly(3,4-ethylenedioxythiophene) (PEDOT)/TiO2 composite fibers were fabricated and applied as the supercapacitor electrode materials. TiO2 fibers were prepared as substrates for the vapor-phase polymerization process, by electrospinning and calcination in air. The symmetric supercapacitor cells assembled with the resulting composites were studied by a series of electrical measurements including cyclic voltammetry, charge-discharge characterization and electrochemical impedance spectroscopy. To further understand the capacitive behavior, the band gap energy of the composite fibers and the specific surface area of TiO2 fibers calcined at varied temperatures were measured. The highest specific capacitance of PEDOT on TiO2 fibers to date, 87.9Fg−1, was achieved with the composite fibers prepared by vapor-phase polymerization at 50°C on the TiO2 fibers calcined at 550°C. The pseudocapacitance and the reversibility of PEDOT were improved in comparison to other PEDOT/TiO2 binary composites.

Ambient stable large-area flexible organic solar cells using silver grid hybrid with vapor phase polymerized poly(3,4-Ethylenedioxythiophene) cathode

The presence of PSS in solution processed high conducting polymer PEDOT:PSS (PH1000) limits the reliability and lifetime of organic photovoltaic devices due to its acidic and hygroscopic nature. We have developed an alternative PSS-free transparent electrode, based on vapor-phase polymerized (VPP) PEDOT in combination with a current collecting silver grid. The hybrid electrode exhibits a low sheet resistance of 1.6Ω/□ with an excellent bending proof performance. The power conversion efficiency (PCE) is 2.63% in a 1.21cm2 area device with a stacking structure of PET/Ag-grid/VPP-PEDOT/ZnO/poly[(9,9-bis(3-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)](PFN)/poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PC61BM)/MoO3/Al. This efficiency is lower than, but comparable to the PCE (3.36%) of a control device with similar structure PET/Ag-grid/PH1000/ZnO/PFN/P3HT:PC61BM/MoO3/Al. A striking advantage using VPP-PEDOT to replace PH1000 is the high ambient stability of the device. The PCE of un-encapsulated devices after 120h continuous exposure to ambient oxygen and moisture is retained at a 75% level of its initial value. These results suggest that the Ag grid/VPP-PEDOT is a promising alternative to ITO or high conducting PEDOT:PSS for realization of high efficiency, low cost and stable organic solar cells (OSCs).

Feasibility test of spray-coating method for patterning of vapor phase-polymerized poly(3,4-ethylenedioxythiophene) thin film

In this study, spray-coating has been opted to prepare patterned Poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes for an organic thin film transistor (OTFT). The conducting polymer was grown via the vapor phase polymerization (VPP) method. The film quality of VPP-PEDOT critically relies on the uniformity of oxidant film selectively patterned on a thermally oxidized Si-wafer surface prior to the polymerization. Therefore, to improve the uniformity of the oxidant film, this study tried to discover best conditions of spray-coating. Several different temperatures of Si-wafer substrate, distances from nozzle to wafer, and spray times were tested during the spray coating process. Then, sprayed oxidant films and vapor phase-polymerized PEDOT patterns were characterized by several thin film analyzing tools such as FE-SEM and optical microscope. The characterization found that the best conditions of spray coating are room temperature, 18cm, and 50s of substrate temperature, spray distance, and time, respectively.

Effect of HF and Plasma Treated Glass Surface on Vapor Phase-Polymerized Poly(3,4-ethylenedioxythiophene) Thin Film : Part I

In this study, in order to investigate how consecutive treatments of glass surface with HF acid and water vapor/Ar plasma affect the quality of 3-aminopropyltriethoxysilane self-assembled monolayer (APS-SAM), poly(3,4-ethylenedioxythiophene) (PEDOT) thin films were vapor phase-polymerized immediately after spin coating of FeCl3 and poly-urethane diol-mixed oxidant solution on the monolayer surfaces prepared at various treatment conditions. For the film characterization, various poweful tools were used, e.g., FE-SEM, an optical microscope, four point probe, and a contact angle analyzer. The characterization revealed that HF treatment is not desirable for the synthesis of a high quality PEDOT thin film via vapor phase polymerization method. Rather, sole treatment with plasma noticeably improved the quality of APS-SAM on glass surface. As a result, a highly dense and smooth PEDOT thin film was grown on uniform oxidant film-coated APS monolayer surface.

A Solid-State pH Sensor for Nonaqueous Media Including Ionic Liquids

We describe a solid state electrode structure based on a biologically derived proton-active redox center, riboflavin (RFN). The redox reaction of RFN is a pH-dependent process that requires no water. The electrode was fabricated using our previously described 'stuffing' method to entrap RFN into vapor phase polymerized poly(3,4-ethylenedioxythiophene). The electrode is shown to be capable of measuring the proton activity in the form of an effective pH over a range of different water contents including nonaqueous systems and ionic liquids (ILs). This demonstrates that the entrapment of the redox center facilitates direct electron communication with the polymer. This work provides a miniaturizable system to determine pH (effective) in nonaqueous systems as well as in ionic liquids. The ability to measure pH (effective) is an important step toward the ability to customize ILs with suitable pH (effective) for catalytic reactions and biotechnology applications such as protein preservation.

Electrocatalytic reduction of oxygen at vapor phase polymerized poly(3,4-ethylene- dioxidethiophene) modified glassy carbon electrode

We successfully polymerized poly(3,4-ethylenedioxidethiophene) by vapor phase polymerization technique on rotating glassy carbon disk electrode. The catalytic activity of this electrode towards oxygen reduction reaction was investigated and showed remarkable activity. Rotating disk voltammetry was used to study the kinetics of oxygen reduction reaction by plotting Levich, Koutecky Levich and Tafel plots. It was found that the reduction was mixed diffusion and kinetic controlled. The O 2 reduction underwent through four electron transfer reaction. The Tafel slope was obtained as 55 mV/dec. The limiting current density was higher by a factor of more than 10 3 times the exchange current density. KEYWORDS : Poly(3,4-ethylenedioxidethiophene), Vapor phase polymerization, Oxygen reduction, Glassy carbon electrode Bull. Chem. Soc. Ethiop. 2012 , 26(3), 449-454. DOI: http://dx.doi.org/10.4314/bcse.v26i3.14

High‐Performance Metal‐Free Solar Cells Using Stamp Transfer Printed Vapor Phase Polymerized Poly(3,4‐Ethylenedioxythiophene) Top Anodes

AbstractThe use of vapor phase polymerized poly(3,4‐ethylenedioxythiophene) (VPP‐PEDOT) as a metal‐replacement top anode for inverted solar cells is reported. Devices with both i) standard bulk heterojunction blends of poly(3‐hexylthiophene) (P3HT) donor and 1‐(3‐methoxycarbonyl)‐propyl‐1‐phenyl‐(6,6)C60 (PCBM) soluble fullerene acceptor and ii) hybrid inorganic/organic TiO2/P3HT acceptor/donor active layers are studied. Stamp transfer printing methods are used to deposit both the VPP‐PEDOT top anode and a work function enhancing PEDOT:polystyrenesulphonate (PEDOT:PSS) interlayer. The metal‐free devices perform comparably to conventional devices with an evaporated metal top anode, yielding power conversion efficiencies of 3% for bulk heterojunction blend and 0.6% for organic/inorganic hybrid structures. These encouraging results suggest that stamp transfer printed VPP‐PEDOT provides a useful addition to the electrode materials tool‐box available for low temperature and non‐vacuum solar cell fabrication.