Lightweight Thin-Film Solar Cell with Periodic Optical Nanostructures

AmberWave, Inc. has previously developed a method to electrically and mechanically integrate an ultra-thin monocrystalline Si layer to a conductive and fracture-resistant supporting layer such as a steel alloy foil. This Ultra-Thin Silicon (UTSi) approach has been used to demonstrate flexible solar cells with over 17% efficiency at under 20 microns silicon thickness. For this Phase II effort, working with our partner NRL we improved upon key elements of the UTSi solar cell develop under our Phase I program, and continued to explore integrating periodic optical nanostructures with the UTSi solar cell to boost rear internal reflectance and increase solar cell effective optical thickness. Key achievements of this program were demonstration of UTSi solar cells with combined area of over 1 ft2 and output power density 7.6 W/ft2 (up to 11.9 W/ft2) and specific output power 35 W/lb (up to 106 W/lb). All of these values exceed the Phase II targets for this topic. In addition, we developed a cost model showing how this technology can be scaled up to enable large-area lightweight portable solar panels at an estimated $5/watt price, 50% lower than the Phase II topic target.