Ultra-lightweight amorphous silicon solar cells deposited on 7.5 μm thick stainless steel substrates

To significantly reduce the solar cell weight and increase its specific power for space application, the authors deposited a-Si thin film solar cells on ultra-thin stainless steel (SS) substrates of 15 μm, 12.5 μm and 7.5 μm thick and compared the results with those on standard 5 mil. (127 μm) thick SS substrates that they use on a regular basis. To handle these ultra thin SS foils throughout the device fabrication process, they used a carrier method by attaching the ultra-thin SS foils on thicker 127 μm SS substrates. They obtained ultra-lightweight solar cells that have similar performance as solar cells on regular 127 μm substrates, with a V_oc of 0.887 V, a J_sc of 10.8 mA/cm², a FF of 68% and an efficiency of 6.5% for cells without back-reflector. These 6.5% efficient, rollable solar cells deposited on 7.5 μm thick SS substrates exhibit a specific power of 1.08 kW/kg, significant for space power applications