By Prof Uri Banin
|Researcher: Prof Uri Banin|
Department: Faculty of Science, The Center for Nanoscience and Nanotechnology
University: Hebrew University of Jerusalem
The tuning of the bandgap and optical properties of quantum dots (QD) by manipulating their composition and size enhances the performance and efficiency of quantum dot sensitized solar cells (QDSSC).
Two existing techniques for preparation of QDSSC include in-situ preparation of quantum dots onto semiconductors and ex-situ, dual step chemical linker-based preparation. In the first method there is limited control over the QD size and broad size distribution. In the second method, TiO2 electrodes are coated with bi-functional molecular linkers and the electrodes are then immersed in a solution of QDs for deposition. This method resulted in poor photoelectric responses and long deposition times of 24 to 96 hrs.
The current research is of interest to the cleantech, energy, solar cells, nanotechnology, synthesis methods of nanomaterials and nanoprocesses audiences. The research has reached the proof of concept stage and a PCT application has been filed.
Researchers have succeeded in fabricating quantum dot sensitized solar cells (QDSSC) by the electrophoretic deposition of semiconductor such as CdSe quantum dots onto conducting electrodes coated with mesoporous oxide electrodes (for instance, titanium dioxide (TiO2)).
Figure: (a) Illustration of the EPD system; (b) images of 3.4, 4.0 and 5.5nm QDs-TiO2 electrodes after 2 hours of EPD;
The key features of the technology include the following:
- There is no pre-treatment of TiO2 required.
- Deposition time is considerably short; two hours are all that is required for an effective coating.
- The photovoltaic characteristics of the devices are superior when compared with those achieved using a linker approach. The efficiencies obtained in the laboratory was as high as 2.7% under Sun illumination conditions
- The method can be easily extended and applied for preparations of QDSSCs using diverse colloidal quantum dot and quantum rod materials for sensitization.
Quantum-dot-sensitized solar cells are a promising cost-effective option to existing photovoltaic technologies that include crystalline silicon and thin inorganic films.
Researchers are seeking industrial cooperation for continuous research in order to improve the method.
About the Center for Nanoscience and Nanotechnology
Since nanotechnology has gained considerable significance in modern science and technology, the Hebrew University of Jerusalem established the Center for Nanoscience and Nanotechnology. The Center operates within the Faculty of Science and strives to create the required environment for the flow of expertise, knowledge and research between researchers from a range of disciplines that include physics, chemistry, applied and life sciences, medicine and engineering. It strives to bring together scientists from a number of disciplines that deal with nanotechnology. The center has around 40 member groups and desires to expand further by recruiting promising, young, faculty members.