Sharp Corporation has recently announced a breakthrough technology with which it has achieved the world’s highest solar cell conversion efficiency of 35.8%.The best feature of this triple-junction compound solar cell is that it uses photo-absorption layers made from compounds consisting of two or more elements such as indium and gallium.
The space satellites usually use these compound solar cells, due to their high conversion efficiency. To boost the efficiency of triple-junction compound solar cells, it is important to improve the crystallinity in each photo-absorption layer. It is also crucial that the solar cell to be composed of materials that can maximize the effective use of solar energy.
Conventionally, Ge (germanium) is used as the bottom layer due to its ease of manufacturing. The problem is that Ge produces a large amount of current, and the most part of the current is wasted. Scientists claim they have solved this problem by forming a bottom layer from a material with high light utilization efficiency, called InGaAs (indium gallium arsenide).
By using its unique technology for forming layers, Sharp has now succeeded in forming an InGaAs layer. As a result, the conversion efficiency, which had been 31.5% in Sharp’s previous cells, has been successfully increased to 35.8% and the amount of wasted current has been minimized.