Publication

Abstract : Multijunction solar cells based on III-V materials (gallium arsenide (GaAs), aluminum indium phosphide (AlInP), aluminum gallium indium phosphide (AlGaInP), gallium indium phosphide (GaInP), and indium phosphide (InP), etc.) show high efficiency, exceeding 35%, but due to the high production cost and low availability of their constituents, these solar cells are not considered suitable for cost-effective terrestrial applications though they are still very important for space PV applications. Some of the silicon technologies (such as a-Si) have serious implications of the light induced degradation. In order to overcome limitations like light absorption, thickness of the absorber layer, and instability of the devices, the multijunction approaches have been adopted. To work within the limits of intrinsic layer thickness of ~ 300 nm and make use of different light trapping arrangements, the concept of tandem cells using double and triple junctions has been thoroughly pursued worldwide. Multijunction solar cells are used for better utilization of solar spectrum and to improve the stability of the solar cells. GaAs is currently used in multijunction solar cells with other materials. The concentrating solar cell technology uses GaAs solar cells. The production of GaAs crystals can be through a combination of gallium and arsenic pure elements or using trimethyl gallium ((CH3)3Ga) and trimethyl arsenic ((CH3)3As) gases. Trimethyl arsenic detoxifies arsenic (Stýblo et al., 2002; Styblo et al., 2000) is rated as a poisonous material during this process. In case of accidents during the GaAs growth, it can have significant effects on lung, liver, immune, and blood systems (Webb et al., 1984, 1986; Flora and Gupta, 2013). There is little toxicological data on gallium, but it is widely used as a marker/tag in MRI tests, and believed to be safe in small doses (Table 3.4; S.V.T. Coalition, 2009).