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Liten, a CEA Tech institute, has successfully reduced monolike silicon solar cell performance losses due to light-induced degradation to under 2%.
The light-induced degradation (LID) of monolike silicon is responsible for performance losses in solar cells made from the material. Researchers at Liten have reduced these losses to a level that makes the solar cells compatible with the demands of industrial-scale production.
LID in monocrystalline silicon is caused by high concentrations of oxygen, which bonds to boron atoms. In multicrystalline silicon, metal impurities cause degradation. "We posited that LID in monolike silicon could be caused by the simultaneous presence of oxygen and metal impurities. We tested our hypothesis in the lab." And, while the two mechanisms were present, the experiments conducted revealed that LID is predominant in the top of the ingot and that it is the metal impurities that are responsible for degradation in that area.
The researchers then decided to experiment with the thermal treatment processes used to manufacture solar cells to augment a well-understood mechanism called gettering, where the metal impurities are drawn to the surface of the material.
The researchers successfully reduced LID, bringing losses under the 2% mark, without adding any steps to the cell production processes (only the parameters of the thermal treatment process already in use were modified). The result will speed up the industrial scale-up of monolike silicon, which is already underway.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.