(333c) Nanostructure Engineering of Polymer Solar Cells

Energy and environment have become two of the top concerns and challenges of the human beings nowadays, and the two issues are closely related to each other. An estimated over 80% of the world energy supplies are from the burning of fossil fuels such as coal, oil, and natural gas [1]. However, carbon dioxide and other toxic gases released from fossil fuel burning are causing many actual and potential environmental problems such as air pollution and globe warming. In addition, fossil fuel deposits on the earth are not unlimited. Sunlight is perhaps the most abundant, free, renewable, and clean energy source on the earth. While the worldwide energy power consumption in 2006 is less than 20 Terawatts, sunlight provides about 165000 Terawatts power to the earth. Though the commercially available inorganic materials based solar cells have typical photoelectric power conversion efficiencies of over 10%, and a five-year compound annual growth rate (CAGR) of 56% through 2008 of solar cell industry is impressive, the technology is still too expensive for popular or general power supplies. Future generation organic or ?plastic' materials based solar cells appear very attractive for popular solar energy conversion applications where low cost (such as large area), lightweight, and flexible shape are desired. The best photoelectric power conversion efficiencies of currently reported organic/polymer photovoltaic materials is still relatively low (about 5-7%), but there is a large room for improvements. This presentation will first provide an overview on the history, fundamental mechanisms, and current status of organic/polymeric photovoltaic materials and devices [2]. A number of approaches including approaches pursued at the speaker's lab will be presented. Prospective and ways of further improving organic/polymeric solar cells will also be briefly addressed. [1] Sun, S and Sariciftci, N. eds., Organic Photovoltaics: Mechanisms, Materials and Devices (ISBN 0-8247-5963-X). CRC Press/Taylor Francis, Boca Raton, Florida, USA, 2005. [2] Sun, S. ?Organic and Polymeric Solar Cells?, in Handbook of Organic Electronics and Photonics, edited by S. H. Nalwa, American Scientific Publishers, Los Angeles, California, 2006, vol. 3, chapter 7, pp 314-350.