Lightweight, High-Efficiency Solar Cell Sheets Using Epitaxial Liftoff
R. Chan, C. Youtsey, G. Hillier, D. McCallum, N. Pan
MicroLink Devices, US
Keywords: solar cell, epitaxial liftoff, lightweight, high efficiency
Abstract:MicroLink Devices will describe its work on making high-efficiency, lightweight, flexible solar cell sheets for use in unmanned aerial vehicles and spacecraft. These solar sheets are based on MicroLink’s proprietary epitaxial liftoff technology, in which the GaAs-based multijunction solar cell structure is removed from the semiconductor substrate on which it is grown. This epitaxial liftoff process is accomplished without damaging the substrate, which can be reused for other solar cell growths. The solar cells are fabricated with features that make it easy to connect the cells in series. To fabricate the solar sheet, the cells are bonded to a backsheet material in an array; interconnects and bypass diodes are added. The cell design means that all interconnection can be done from the top side of the array. After interconnection, a topsheet material is applied over the cell array and is vacuum laminated into place. Depending on the application and operating environment, the top and bottom film sheet materials and cell metallization can be varied for an ultra-lightweight sheet or improved mechanical ruggedness. The areal density of the sheet is expected to be a few hundred grams per square meter.