B.Sc., Ph.D. (Carleton)
Plastic Solar Cells Utilizing Mixed Organic Crystals For Broad Spectral Absorption
Have you ever wondered why your inkjet printer comes with inks of the colours cyan, magenta and yellow? Ink jet prints and colour laser prints for that matter, are reflective displays and as such require the use of materials that absorb certain wavelengths of visible radiation and reflect the rest. In the absence of any ink the colour is white, reflecting back to you all wavelengths of visible light. Whereas in the presence of all three inks the colour is black because the mixture absorbs all wavelengths of radiation visible to the human eye. What fundamental materials property is important for the formation of a colour image? In the case of a reflective display it is the materials’ absorption spectrum. Cyan, magenta and yellow are chosen since each colour has a unique absorption spectrum and the combination in the solid state cover the entire visible electromagnetic spectrum.
Why a brief diversion into aspects of colour science when the title of this proposal says ‘solar cells’? In most, if not all, the published accounts of organic based photovoltaic cells a single organic compound, a dye or a pigment/crystal, is responsible for absorption of the incident radiation. This single organic compound has a unique absorption spectrum and it is usually in the visible or ultraviolet regions of the electromagnetic spectrum. The sun emits large amounts of electromagnetic radiation across a large range of wavelengths. Therefore, using a single compound in a photovoltaic is neglecting a large portion of the available electromagnetic radiation in a direct analogy to trying to use a single colourant to make a full colour print.
Organic/plastic solar cells can be readily manufactured in a cost effective way by slot-die coating or by other simple readily available printing technologies in only a moderately clean environment. As such, they have the potential to provide a real ROI for the average consumer whereas current silicon technology currently can not. As of 2006 little has been done to cost-down silicon photovoltaics and the technical advances in light harvesting efficiency and device stability necessary to bring organic solar to the market have yet to be made.
Prof. Bender proposes research focused toward the design, engineering and application of new materials to enable a plastic/organic solar cell to harness ALL of the incident radiation received from the sun and to convert that radiation into electrical energy. This will be accomplished by the use of a novel array of phthalocyanines pigments/crystals (organic materials known to absorb light and produce electrical charge) that when used together will produce a flexible, organic solar cell capable of absorbing all of the incident radiation from the sun. By absorbing all of the radiation available, the amount of electrical energy produced will be increased: more absorption means more electricity: provide suitably long exciton lifetimes and suitable efficient electron transfer rates can be achieved. Along with this set of phthalocyanine pigments/crystals, polymeric hole- and electron-transporting materials will need to be designed and synthesized. Their responsibility in the integrated photovoltaic device is to move the generated electrical charge to their respective electrodes thereby completing an electrical circuit and generating electrical current.
Prof. Bender uses a unique approach to research: the full integration of computer aided molecular modeling and materials design, chemical synthesis and engineering, and chemical characterization, into materials design, synthesis and discovery and therefore provides a unique ability to expose students to the entire material design cycle. By being a part of a lab of this nature not only will students gain experience in the interaction with people of different academic levels but also with people of differing interests all working towards the same high level goal. Achieving a level of appreciation for what each brings to the R&D environment ahead of entering the Canadian or International work force will be invaluable to their future employers. While the research focus of the lab will be organic solar cells, the techniques and skills utilized in the pursuit of this research are directly translatable to other chemical sectors including organic electronic chemicals, other high value added materials (e.g. catalysts) and fine chemicals (e.g. pharmaceuticals). A research laboratory using this three-step approach and focused on advanced organic materials design, synthesis and engineering would be unique within the Greater Toronto Area/Ontario/Canada context and indeed uniquely positioned within only a handful of such labs around the world.
Students in his laboratory will have exposure to and become experts in:
- Computer aided molecular design
- Materials design, synthesis, purification and characterization
- Materials structure/property relationships
- Functional device fabrication and evaluation
- Scale up process engineering
- Experimental design (including Taguchi designs).
Prof. Bender is an established expert in the field of organic electronic materials, specifically in their industrial application to organic photoreceptive devices. He has filed over 50 US Patents (17 currently issued) and authored or co-authored 17 peer reviewed papers in the fields of organic electronic materials and polymeric structures. While at Xerox he participated in and chaired several high level committees including a committee reporting directly to the Chief Technology Officer of Xerox Corp. (Global).