Research Group – Prof. Dr. Ayşegül UYGUN ÖKSÜZ

PEDOT/WO3 Hybrid Nanofiber Architectures for High Performance Electrochromic Devices.

Electrochromic devices (ECDs) are of much current interest for a wide range of applications, including color displays, sensors, reflectance mirrors, vehicle sunroofs and smart windows. WO3 is perceived as a prospective candidate for ECDs since it has many advantages such as genuine color switching and, good chemical stability and exhibits the most efficient electrochromic properties both in the visible and near infrared regimes. These properties are substantially dependent on the crystal structure, which in turn affects the electronic properties of the ion injection/ejection during electrochemical reactions.

Investigation of the effects of plasma-treated chitosan electrospun fibers onto biofilm formation.

Surface modification of polymers is an important technique in developing physicochemical polymer properties. The various surface modification techniques including the mechanical, physical, chemical and biological methods were used to modify the surface properties of polymers. Thanks to these different methods, the polymers may have different properties such as biocompatibility, wettability and functionality. However, the applications of the chemical and mechanical methods currently used to modify polymer surfaces are limited (e.g., hazards associated with chemical wastes and problems related to changes below micrometers).

Polyfuran-based multi-walled carbon nanotubes and graphene nanocomposites as counter electrodes for dye-sensitized solar cells.

Since 1991, dye-sensitized solar cells (DSSCs) have attracted academic and commercial attention around the world due to their low cost and simple fabrication. DSSCs can convert sunlight into electricity, and their efciencies have increased over time. The properties of the working electrode, counter electrode and electrolyte can afect the performance of DSSCs. In recent years, eforts have been made to reduce the cost of DSSCs by exploring new counterelectrode materials to replace platinum, which is expensive and rare. Polyfuran (PFu) is a heterocyclic aromatic compound that has been extensively studied due to its reactivity, high conductivity and specifc physicochemical properties.

Ibuprofen and acetylsalicylic acid loaded electrospun PVP-dextran nanofiber mats for biomedical applications.

Electrospinning is a unique technique for producing nano- and micro-sized continuous polymer fibers. Electrospun nanofibers are excellent candidates in filtration, drug delivery systems, in separation membranes, as reinforcement in composite materials and medical devices, as well as in biomaterials for wound dressings and scaffolds for tissue engineering. Electrospinning is capable of producing ultrafine fiber with nanometer range diameters using natural and synthetic polymers, which yield very high specific surface areas, up to one to two orders of magnitude higher than current microfibers produced from conventional melting and dry/wet spinning methods.

Synergistic tungsten oxide/organic framework hybrid nanofibers for electrochromic device application.

Electrochromism is described as the reversible color change of a material between the redox states induced by application of an electrical potential. Electrochromic devices (ECDs) are able to control the throughput of visible light and solar radiation entering the buildings and provide energy efficiency by modulating optical transmittance. ECDs have many application areas such as smart windows of green buildings, full-angle information displays, controlled reflectance mirrors and thermal control of satellites. Various chemical compounds have been investigated and developed for the ECDs, such as inorganic complexes, organic molecules, metallo-supramolecules, electroactive polymers and metal oxides.

Electrochromic characteristics of radio frequency plasma sputtered WO3 thin films onto flexible polyethylene terephthalate substrates.

In electrochromic materials optical features change when voltage is applied across them. The optical features should be reversible; i.e. the original state should be recoverable if the polarity of the voltage is changed. These features make electrochromic materials of substantial interest for several applications such as smart windows, wearable displays, mirrors and television screens. An electrochromic device (ECD) behaves like a thin film battery that changes optical properties with oxidation reactions. An ECD has at least one electrochromic layer as well as anode, cathode and electrolyte components.

QCM-DNA biosensor based on plasma modified PT/TiO 2 nanocomposites.

A significant development in this field was recorded with the design of DNA biosensors. DNA biosensors are generally greatly enhanced for diagnostic applications, environment monitoring, genetic analysis, food controls, detection of genetically modified organisms, and bacteria or virus detection. As a mass-sensitive device capable of measuring subnanogram levels, the quartz crystal microbalance (QCM) is an important technology to design sensitive DNA biosensors. QCM sensor provides a number of excellent benefits as a label free recognition system such as rapid detection, easy adjustment, and cost effectiveness by reducing reagents and efforts.