Kamil Zuber

Structure-directed growth of high conductivity PEDOT from liquid-like oxidant layers during vacuum vapor phase polymerization

Vapor phase polymerization (VPP) is at the forefront for synthesizing high conductivity poly(3,4-ethylenedioxythiophene) (PEDOT) as an alternative to indium tin oxide (ITO). Little attention, however, has been directed to the oxidant layer used in the polymerization process. In this study the observation of an oxidant layer (oxidant + PEG–PPG–PEG) possessing liquid-like properties during the vacuum synthesis of PEDOT is reported. This is in contrast to the other oxidant layer variants studied which are observed as solid (pristine oxidant) or gel-like (oxidant + pyridine). Tailoring of the liquid-like properties leads to confluent PEDOT films with a conductivity of 2500 S cm−1, placing this PEDOT within the conductivity range of commercially available ITO. Building on the liquid-like observation, XPS and ToF-SIMS experiments reveal that PEDOT growth is via a bottom-up mechanism with transportation of new oxidant up to the forming PEDOT layer.

Influence of PEG-ran-PPG Surfactant on Vapour Phase Polymerised PEDOT Thin Films

The oxidant, Fe(III) tosylate, was used in the vapour phase polymerisation (VPP) of PEDOT. The amphiphilic co-polymer poly(ethylene glycol-ran-propylene glycol) was added and its influence examined. Both the PEDOT conductivity and optical contrast range increased with the inclusion of the co-polymer, with the maximum being recorded at 4 wt.-%. Loadings higher than this resulted in a systematic decrease in both conductivity and optical contrast. Evidence indicates that in addition to the beneficial anti-crystallisation effect to the oxidant layer, the co-polymer also reduces the effective reactivity of the oxidant, as demonstrated by slower polymerisation rates. Confirmation of the change in polymerisation rate was obtained using a quartz crystal microbalance (QCM). The slower polymerisation rate results in higher conductivity and optical contrast; however, XPS data confirmed that the co-polymer remained within the PEDOT film post-washing and this result explains why the performance decreases at high surfactant loadings.

Effect of oxidant on the performance of conductive polymer films prepared by vacuum vapor phase polymerization for smart window applications

Conductive polymers synthesized by vacuum vapour phase polymerization (VPP) were investigated and optimized by changing the oxidant solution and VPP chamber parameters for their incorporation into ?smart window? electrochromic devices. Additionally, the interaction of two oxidant solutions with typical electrode materials (aluminium and indium tin oxide) were examined with respect to material etching, device cosmetics and long term device degradation (over 10 000 switch cycles). Devices made with conducting polymers synthesized with the oxidant Fe(Tos)3 rather than FeCl3 produced superior device performance with respect to optical switching range (%T), switch speed and optical relaxation.

Nanoporous glass films on liquids.

Glass-like thin films are used in many applications as dielectric layers, barrier coatings, abrasion-resistant films, and/or transparent films. We report the first direct application of such materials to liquid substrates using a plasma-deposition process at atmospheric pressure. The study demonstrates the broader utilization of these materials, for example, as robust membranes for water harvesting or drug delivery.

Optical coatings for automotive applications: a case study in translating fundamental materials science into commercial reality

Translating fundamental scientific research into commercial reality is not a natural fait accompli progression for the majority of academics. An established scientific entrepreneurial cultural mindset needs to exist within the research group for this translation to occur in a meaningful and productive manner. This investigation outlines a scientific case study; the world’s first original equipment manufacturer plastic automotive reflector. This is now a mature product in the market place, and the case study incorporates the organizational mindset, contractual overview, scientific progression and engineering evaluation needed to bring the project to fruition. The study demonstrates that rather than being an impediment to achieving a successful academic/industry partnership, concurrently running a fundamental research program and an applied science program actually produces tangible benefits. Importantly, however, both partners (academic and industrial) need to understand the benefits that can be realized in running parallel programs from the outset and importantly that both parties actively contribute to the project from the outset. The questions that are raised in each program, and importantly the technical answers/understanding which are developed, help drive the overall progress of the project.

Large Area Nanostructured Arrays: Optical Properties of Metallic Nanotubes

In this study, large area metallic nanotube arrays on flexible plastic substrates are produced by templating the growth of a cosputtered alloy using anodized aluminum oxide membranes. These nanotube arrays are prepared over large areas (ca. squared centimeters) by reducing the residual stress within the thin multilayered structure. The nanotubes are approximately 20 nm in inner diameter, having walls of <10 nm in thickness, and are arranged in a close packed configuration. Optically the nanotube arrays exhibit light trapping behavior (not plasmonic), where the reflectivity is less than 15% across the visible spectra compared to >40% for a flat sample using the same alloy. When the nanotubes are exposed to high relative humidity, they spontaneously fill, with a concomitant change in their visual appearance. The filling of the nanotubes is confirmed using contact angle measurements, with the nanotubes displaying a strong hydrophilic character compared to the weak behavior of the flat sample. The ability to easily fabricate large area nanotube arrays which display exotic behavior paves the way for their uptake in real world applications such as sensors and solar energy devices.

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.