Plastic Solar Cells Photovoltaics

Diverse strategies that ultimately would improve the processibility of functionalized fullerene materials and obtain their intimate mixing with conjugated polymers have been proposed. In more detail, the following systems have already 

Novel hybrid materials have been realized in which fullerenes participate in composite films with 7r-conjugated-polymer electron donors such as oligothio-phenes. Established studies have already shown that the photoinduced electron transfer is rather enhanced between 7r-conjugated polymers and fullerenes, while back electron transfer is considerably slower [145,149,171,172].Electrosynthe-sized polythiophene with pendant fullerene substituents was recently obtained from the corresponding biothiophene-fulleropyrrolidine dyad [173]. The novel material described has the potential of a double-cable polymer, heavily loaded with fullerene electron-conducting moieties. 

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Spectral Sensitization. One of the limiting factors in plastic solar cells is their mismatch with regard to the solar spectrum. Typically, conjugated polymers like MDMO PPV, used for photovoltaics, have their peak absorption around 500 nrn. This is significantly offset from the maximum in the photo-flux of the sun, which peaks around 700 nm. 

Arid E, Hoppe H, Reuning A, Sariciftci NS, Meissner D (2002) CIS plastic solar cells. Presented at the 17th European photovoltaic solar energy conference, Munich, 22-26 October 2001, p 61... 

Nelson, (a) Organic and Plastic Solar Cells, Chapter IIe-2 in T. Markvart, L. Cataner (eds.). Practical Handbook of Photovoltaics Fundamentals and Applications, Elsevier, Oxford (2003) (b) Materials Today 5 (2002) 20. 

One of the problems facing manufacturers of polymer-based photovoltaic cells is their low light-to-energy conversion efficiency of 5% maximum, whereas multi-junction crystalline silicon-cells have achieved a figure of 37%. One of the flexible plastic solar cells exhibiting the 5% efficiency contains zinc oxide. 

Yet another development, at the University of Toronto in Canada, is based on the discovery of the first plastic material to absorb infra red light. This achievement came about as a result of doping a polymer with nanometre-sized semiconductor particles that were tuned to absorb in the infra red region of the frequency spectrum. Not only had the research team discovered what was claimed to be the world s first infra red detector which could be painted but also the world s first infra red photovoltaic detector. The researchers believe that, by combining infra red and visible photovoltaic processes, it could be possible to reduce the cost of solar energy since the current 6% best efficiency figure for plastic solar cells might even be raised to 30%. 

Because of the advantages that would be realized with polymer-based photovoltaics, such as low cost fabrication in large sizes and in desired shapes with mechanical flexibility, efficient plastic solar cells would have a major impact. 

K. Lee, J. Y. Kim, and A. J. Heeger. 2008. Titanium oxide films as multifunctional components in bulk heterojunction "plastic" solar cells. In Organic Photovoltaics Materials, Device Physics, and Manufacturing Technologies, ed. C. Brabec, V. Dyakonov, and U. Scherf. Weinheim WUey-VCH. 

Apart from plastic frames for solar cells, there is intensive development work to use polymer films as cheap and flexible photovoltaic materials. 

Schlettwein, Yoshida, and Lincot provide a critical review of the research literature on porous zinc oxide sensitized by organic dyes, and the potential use of these materials for the development of large-scale photovoltaic solar cells. An introduction is provided to the electrodeposition of zinc oxide thin films, their means of sensitization by a variety of organic molecules, and their preparation by one-step deposition from solutions containing water-soluble dyes to produce hybrid materials suitable for solar cell. The advantages of various substrates for large-scale cells are discussed for plastic and textile materials. 

BaUat J et al. (2005), Recent development of solar cells on low-cost plastic substrates, In Proceedings of the 20th EU Photovoltaic Solar Energy Conference, Barcelona, Spain, pp. 1529-1532... 

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