Ultrathin GaAs Photovoltaic Arrays Integrated on a 1.4 µm Polymer Substrate for High Flexibility, a Lightweight Design, and High Specific Power

Abstract

Lightweight ultrathin solar cells with high efficiency and reliability serve as a convenient untethered power source for new types of electronic devices, such as attachable or implantable electronics, small-scale robots, and many others. However, the extreme mechanical properties of high-performance solar cells and ultrathin films present challenges when handling and processing them to realize ultrathin solar cell arrays. In this paper, a highly efficient GaAs photovoltaic array integrated on an ultrathin polymer film (1.4 µm thick) is presented. Full processes, including framing, cold-welding, epitaxial lift-off (ELO), and microfabrication, are used to realize ultra-flexible and lightweight GaAs photovoltaic arrays. The mechanical characteristics are analyzed via numerical and experimental methods along with demonstrations with electrically functional devices. The power-to-weight ratio (specific power: 5.44 W g−1) is in the highest range, even with single-junction solar cells.