ABSTRACT
Photovoltaic Effect was discovered in 1839 by Edmund Becquerel. But it was not until 1883 that the first solar cell was built by Charles Fritts. He shone light upon a layer of selenium covered with a layer of gold and generated electricity. The first use of a silicon semiconductor solar cell, made by Bell Laboratories in New Jersey, USA, was to power the second American spacecraft Vanguard 1 in 1958. The most advanced photovoltaic cells are still used to power spacecraft. It is really space flight which has propelled the development of the technology. Standard crystalline silicon cells (c-Si) are made of two layers of silicon, one of which is 'dosed' with atoms of phosphorous, and the other with boron, to give them opposite electrical charges. The amount of light energy, and which frequencies of light are able to dislodge the electron, is determined by the 'band gap' of the material.
