Sharp Achieves Record 35.8% Conversion Efficiency with Triple Junction Compound Solar Cell
Source/Type: Reported News

Author: CompoundSemi News Staff

November 4, 2009... Sharp Corporation of Japan reports having achieved what it says is the world’s highest solar cell conversion efficiency of 35.8% using a triple-junction compound solar cell. Sharp points out that when boosting the efficiency of triple-junction compound solar cells, it is important to improve the crystallinity (the regularity of the atomic arrangement) in each photo-absorption layer (the top, middle, and bottom layer). Sharp also notes that it is crucial that the solar cell be composed of materials that can maximize the effective use of solar energy.

The new solar cell designs, like their previous versions have an indium gallium phosphide top layer. However, instead of having an (indium) gallium arsenide (In)GaAs middle layer, the new design has a gallium arsenide (GaAs) middle layer. Then, instead of having a germanium (Ge) bottom layer, the new design uses an InGaAs bottom layer. Sharp researchers say that a germanium bottom of previous cells layer can generate a lot of current, but much of it is wasted without being converted to electrical energy.

Sharp succeeded in forming an InGaAs layer with high crystallinity by using its proprietary technology for forming layers. The company says that in this way, the amount of wasted current was minimized. This boosted the conversion efficiency, which had been 31.5% in Sharp’s previous cells to 35.8% in the new cells. Sharp achieved this efficiency improvement as part of a research and development initiative promoted by Japan’s New Energy and Industrial Technology Development Organization (NEDO) on the theme of “R&D on Innovative Solar Cells”. Sharp Corporation News Release

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