A triple-junction compound solar cell, with three stacked photo-absorption layers, has the highest conversion efficiency. This incredible achievement came from a research and development initiative at Sharp Corporation. It is promoted by Japan’s New Energy and Industrial Technology Development Organization (NEDO) on the theme of “R&D on Innovative Solar Cells.
The new world record of 37.7% was confirmed by the National Institute of Advanced Industrial Science and Technology (AIST).
The photo-absorption layers are made from compounds containing at least two elements, for example indium and gallium. Sharp’s own technology used within the structure of the triple-junction compound solar cell allows stacking of the layers efficiently, where indium gallium arsenide (InGaAs) is in the bottom layer.
The key to Sharp’s success was hidden in the ability of the new cell to absorb and convert light from different wavelengths into electricity. To achieve this record efficiency, Sharp also increased the size of the active area for converting light to electricity by optical processing of the edges of the cells. These two combined increased the maximum output levels of the solar cell, and hence the efficiency.
The company is now planning to implement this technology into concentrator photovoltaic power systems that convert and collect sunlight into electricity using lenses. Sharp’s officials are certain that these cells will be applicable in many fields and technologies, including space satellites and vehicles.