Warwick team pressing for more solar energy

摘要

Researchers at Warwick University have demonstrated that more energy could be generated by photovoltaicsolar cells by deforming the crystals within the semiconductors, simply by pressing on them.Silicon solar cells typically consist of two layers: p- and n-type semiconductors, which are placed togetherto form a p-n junction.When light is absorbed by the cell, this p-n junction generates an internal field within the device, which splits the charge carriers in opposite directions, generating a current and voltage acrossthejunction.While such junctions play a crucial role in extracting power from solar cells, they have a fundamental efficiency limit, known as the Shockley-Queisser limit.This means that only 33.7 percent of the power contained in sunlight falling on an ideal solar cell in ideal conditions canbe converted into electricity. To find out if this limit could be overcome, the researchers turned to a less well-known effect known as the bulkphotovoltaic effect. This effect is only found in certain semiconducting materials which have a lack of symmetry around their central point, known as a non-centrosymmetric structure, according to Prof Marin Alexe, who led the research."This is a type of symmetry which allows for the spontaneous splitting of those light-induced carriers without any requirement for a p-n junction," said Alexe.