Prof. Zaban's Lab
Head - Bar-Ilan Institute of Nanotechnology & Advanced Materials (BINA)
Renewable Energy and Materials Science
Prof. Arie Zaban, of the Department of Chemistry, is Director of Bar-Ilan’s Institute of Nanotechnology and Advanced Materials (BINA) and its Nano Energy Center. Zaban's major areas of interest include photovoltaics and the development of materials for this industry, using high throughputscreening and combinatorial chemistry. Based on over 14 years of research in the field of dye-sensitized solar cells, Zaban's group has recently extended its activity to the development of quantum dot sensitized devices and flat multilayer solid state cells. Their goal is to improve the current understanding of nano-composite solar cells in order to break the current solar cell efficiency limits.
Dye Sensitized Solar Cells as an Alternative to Silicon
Single crystal silicon solar cells are currently the paradigm in solar cell technology, achieving around 25% conversion efficiency in record cells. However, these cells are still too expensive for large scale production. Research in Zaban’s lab focuses on new approaches for large-scale generation of clean electricity by photovoltaic (PV) systems, producing highly efficient and low-cost electrical power.
Dye Sensitized Solar Cells (DSSC), also referred to as the "2nd generation PV," are currently a leading, low cost photovoltaic alternative to silicon based solar cells. DSSCs make use of dyes to generate electrons, thus enabling the use of less costly semiconductors, such as colorless titanium oxide, for electrodes, rather than silicon.
Zaban's research team recently developed more efficient DSSCs using plastic substrates. This new, low-temperature method is used to produce conformal coatings on non-sintered, pre-formed mesoporous electrodes, using a combination of sol–gel processing and electrophoretic deposition (EPD) to improve the electronic connection between nano-crystals, and to suppress recombination.
Quantum Dot Sensitized Solar Cells
Zaban and his group study mono- and poly-disperse quantum-dot-sensitized solar cells (QDSCs), focusing on stability, coating methods and performance. In a study related to Type II dye-sensitized solar cells – in which electrons are injected from the sensitizing dye directly into the conduction band of the semiconductor – Zaban presented a new approach for inhibiting back electron transfer. Using a thin barrier coating between the semiconductor and the sensitizer, he achieved a 70% improvement in charge collection efficiency.
In another study, Zaban showed that by modifying electrodes of QDSCs with both molecular dipoles and conformal coatings, it becomes possible to both increase injection and reduce recombination. This boosts the energy conversion efficiency of the devices.
In another project, Zaban's group is working on a new design for DSSC, combining the broad absorption spectrum of QD's with the evolved charge transfer mechanism of DSSC. In their design, QDs serve as “antennas”, funneling absorbed energy to nearby dye molecules via FRET- a non-radiative energy transfer, rather than being used directly as sensitizers. The QDs are incorporated into the nanoporous TiO2 electrode with total isolation from the electrolyte, significantly improving their photostability. This new cell design enhances light absorption and broadens the absorption spectrum, effectively increasing the number of photons harvested by the dye sensitized solar cell.
Combinatorial Materials Science for Next Generation Photovoltaics
Zaban's group is also developing 3rd generation photovoltaic cells using a unique fabrication tool that combines different elements or materials, producing solid state alloys that continuously change their composition. High throughput analysis is used to characterize the new materials and to identify suitable compositions for electrochemical and optical applications. The fabrication tool also enables production of thermodynamically metastable materials of a higher caliber than is attainable by other methods.