High Efficiency Stretchable Photovoltaic Sheets for Expeditionary Forces

MicroLink Devices, in collaboration with UCLA, proposes to develop a photovoltaic sheet with a >20% conversion efficiency and a 30% elastic response to biaxial strains. The photovoltaic sheet will consist of an array of inelastic solar cells connected in series by stretchable conductive interconnects. The interconnects will be either corrugated metal or a serpentine wire. Cells and interconnects will be embedded in an elastic polymer sheet that will provide the elastic response to an externally-applied strain and protect the cells from the environment. The solar cells will be ultra-thin, high-efficiency, GaAs-based multijunction devices. The cells will be manufactured using MicroLink’s proprietary epitaxial liftoff process, which produces thin, flexible, metal-backed solar cells with areas in the range a few square millimeters to several square centimeters. For ease of manufacture, the cells will be fabricated so that access to only one side is needed to fabricate the interconnects. In the Phase I work, key photovoltaic sheet design parameters, including cell size, cell spacing, encapsulation material, and interconnect material, will be determined from a mechanical model. A scheme for interconnecting and encapsulating the cells will be developed, and some cells will be fabricated and interconnected.