Đang chuẩn bị liên kết để tải về tài liệu:
Solar Cells Silicon Wafer Based Technologies Part 7

Tham khảo tài liệu 'solar cells silicon wafer based technologies part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Silicon-Based Third Generation Photovoltaics 141 spectrum or air mass zero AM0 spectrum is richer in ultraviolet light than the typical terrestrial solar spectrum air mass 1.5 or AM1.5 . Taking into account that the ultraviolet light is converted into electricity less efficiently than the other parts of the spectrum the resulting efficiencies for AM0 are thus lower Green et al. 2010 . Since cells are typically measured under the spectrum for their intended use and efficiencies are not easily converted this chapter will indicate efficiencies measured under non-concentrated AM1.5 at 25 unless otherwise specified. Fig. 3. Schematic view of GaInP GaAs Ge solar cell. Fig. 4. Using of multijunction solar cells for Mars rover missions 1. Up today the tandem cells have been developing on monolithic integration of non-abundant III -V materials by means of rather expensive technologies of fabrication like molecular beam epitaxy MBE or metal-organic chemical vapor deposition MOCVD . Currently commercially available multijunction cells consist of three subcells GaInP GaAs Ge which all have the same lattice parameter and are grown in a monolithic stack Fig. 3 . The subcells in this monolithic stack are series connected through the tunnel junctions. The record efficiency of 32 was achieved in 2010 for this type of cells Green et al. 2010 . These high-efficiency solar cells are being increasingly used in solar concentrator systems where development of both the solar cells and the associated optical and thermal control elements are actively being pursued. The performance of tandem solar cells has been demonstrated but work is continuing to increase the numbers of junctions and optimize the bandgap junctions. The choice of materials with optimal or near-optimal bandgap is severely limited by the lattice matching constraint of these cells. Another approach to increasing of multijunction solar cell efficiency is the incorporation of materials with a mismatch in the lattice constant.