High-efficiency thin-film GaAs bifacial solar cells

Thin-film GaAs bifacial solar cells, which consist of only 5 μm of GaAs fabricated by the cleavage of lateral epitaxy for transfer (CLEFT) process, are designed to produce power from light entering both the front and back sides of the cells. In terrestrial applications, these cells can efficiently convert scattered light from the ground below and adjacent to the array such as from white sand or white paint. For applications in space, the Earth´s albedo would provide back illumination to boost the cell output. A 4 cm² cell was found to be 22.6% and 12.9% efficient for 1-sun AM 1.5 global illumination from the front and back, respectively. With an improved response from the back of the cell and an optimized geometry for the array, effective cell efficiencies of over 30% are achievable for thin-film GaAs bifacial cells