Solar cells based on silicon

Although conventional solar cells based on silicon are produced from abundant raw materials, the high-temperature fabrication routes to single-crystal and polycrystalline silicon are energy intensive and expensive. The search for alternative solar cells has therefore focused on thin films composed of amorphous silicon and on other semiconductor heterojunction cells (e.g., cadmium telluride and copper indium... 

Solar cells based on silicon or gallium arsenide provide a way to convert the radiant energy of the sun directly into electrical work by a technology that is virtually nonpolluting (Fig. 22.26). The high capital costs of solar cells make them uncompetitive with conventional fossil fuel sources of energy at this time, but as reserves of fossil fuels dwindle, solar energy will become an important option. 

With the development of organic semicondnctors which support electron or hole transport (in analogy of p- and n-type inorganic semiconductors) bilayer type p-n heterojunction devices have been constructed. In the case when organic p- and n-type materials are deposited consecutively in two layers we get lateral heterojunction devices which mimic classical p-n junction junction solar cells based on silicon. The first such cell was designed by Tang and pnb-lished in 1986 (Fignre 3)." Copper phthalocyanine was utilized as electron donor (p-type) material, whereas pery-lene derivative was nsed as electron acceptor connterpart (n-type material). 

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