Solar cells silicon-based

Deng, X. Schiff, E.A. Amorphous silicon-based solar cells. In Handbook of Photovoltaic Science and Engineering Luque, A., Hegedus, S., Eds. Wiley Chichester, 2003 505-565. 

Whether organic solar cells will be commercially employed in the future will be decided by economic aspects. It is certain, however, that their fabrication is simpler and cheaper than that of silicon-based solar cells. Furthermore, they have the advantage that they can be produced on flexible and light substrates. In addition, solar cells based on polymer systems can be fabricated using printing technology. 

At the early development of polymer solar cells, a planar p-n junction structure represented the mainstream in mimicking conventional silicon-based solar cells. However, the obtained devices demonstrated poor photovoltaic performances due to the long distance between the exciton and junction interface and insufficient light absorption due to the thin light absorber. It was not until 1995 that the dilemma was overcome with the discovery of a novel bulk heterojunction in which donor and acceptor form interpenetrated phases. Poly[2-methoxy-5-(2 -ethylhexyloxy)-p-phenylene vinylene] was blended with Ceo or its derivatives to form the bulk heterojunction. A much improved power conversion efficiency of 2.9% was thus achieved under the illumination of 20 mW/cm. (Yu et al., 1995). The emergence of the donor/acceptor bulk-heterojunction structure had boosted the photovoltaic performances of polymer solar cells. Currently, a maximal power conversion efficiency of 10.6% had been reported on the basis of synthesizing appropriate polymer materials and designing a tandem structure (You et al., 2013). The detailed discussions are provided in Chapter 5. 

The modem Gratzel cell is sketched in Figure 13.12. Its efficiency is around 25%. It is important to bring down the price by using cheap sensitizers, electrode materials, and redox systems. One of the electrodes has to be transparent for light. The often-used indium-tin-oxide (ITO) is expensive. It is possible to use instead fluorine-doped SnO. The price of Gratzel cells is considerable lower than the price of ordinary silicon-based solar cells. 

Badescu, V. (2006). Simple optimization procedure for silicon-based solar cell interconnection in a series-parallel PV module. Energy Conversion and Management, 47, 1146-1158. 

A prerequisite for the commercial success of organic photovoltaic devices is a significant reduction of device processing costs compared to conventional, silicon-based solar cells. In OSCs the employment of TCOs as the transparent electrode contributes significantly to the overall costs, as TCOs have to be deposited by slow process techniques, for example, sputtering, and cannot be deposited by cost efficient printing methods. This has motivated approaches that follow alternative materials to substitute TCOs. For a detailed discussion on this topic see Section 10.3. 

S. Y. Myong, S. S. Kim, and K. S. Lim, In situ ultraviolet treatment in an Ar ambient upon p-type hydrogenated amorphous silicon-carbide windows of hydrogenated amorphous silicon based solar cells, Applied Physics Letters, vol. 84, no. 26, pp. 5416—5418, 2004. 

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