Tantalum pentoxide Sulfuric acid Phosphine Sodium hydroxide Zinc Tin Phosphorus trichloride Tin Zinc fluoroborate Silicon Silicon dioxide Silane Silicon trioxide Silicon tetrachloride Silver Sodium hydroxide Stannic chloride Sulfuric acid Tantalum pentoxide Titanium Titanium dioxide Trichlorosilane *List of chemicals and materials was compiled based on personal communication with a representative from ASE Americas Inc. and Siemens Solar Industries. **Indicates a complete list of chemicals and materials used in the manufacturing process. References: SERI, 1981; Fthenakis et al., 1984; Dickson, 1987; Moskowitz et al., 1987; Partain et al., 1987; Moskowitz et al., 1989; Moskowitz, 1992; Moskowitz, 1995; Patterson, 1997; Andersson et al., 1998; Steinberger, 1998; Fthenakis and Moskowitz, 2000 3-2
Handling of Chemicals Used in Photovoltaic Systems Table 3-2 Amounts of Metals in Various Types of PV Cells Cell Type Material Requirements, g/m 2 Amorphous-Si/Ge Sn 3.3 Ge 0.22 Si 0.54 Al 2.7 CdTe Sn 0.66 Cd 4.9 Te 4.7 Mo 10.0 CIGS Zn 9.1 Cu 1.8 In 2.9 Ga 0.53 Se 4.8 Cd 0.19 Mo 10.0 Reference: Anderson et al., 1998 A variety of acids or corrosive liquids are used in fairly large quantities during the manufacturing process. These acids or corrosive liquids include hydrochloric acid, sulfuric acid, nitric acid, and hydrogen fluoride. These chemicals are primarily used for the cleaning of wafers or to remove impurities from raw semiconductor materials. Solvents including 1,1,1-trichloroethane and acetone are also used in large quantities in the various cleaning steps conducted during the production processes. Etching compounds such as sodium hydroxide can also be used in relatively large quantities. The amount of a given chemical used will vary depending upon numerous factors including the type of cell being produced, the amount of material processing required, and the amount of wafer cleaning required. The manufacturing of solar cells involves the use of multiple chemicals classified as hazardous by the Federal Department of Transportation, including highly explosive and toxic gases. A list of such hazardous materials, and a description of each material is given in Table 3-3. It is important to note that this is a general list for the photovoltaic industry and does not pertain to any specific photovoltaic cell type or company. Also, the manufacturing processes are constantly evolving and changing, so it is possible that some of these substances may no longer be used in the manufacturing processes. 3-3
Handling of Chemicals Used in Photovoltaic Systems Table 3-3 Hazard Classification of Chemicals Typically Used in PV Module Manufacturing Material DOT Hazard Classification* Arsenic Poison Arsine Highly Toxic Gas Cadmium Poison Diborane Flammable Gas Diethyl Silane Flammable Liquid Diethyl Zinc Pyrophoric Liquid Dimethyl Zinc Spontaneously Combustible Hydrochloric Acid Corrosive Material Hydrofluoric Acid Corrosive Material Hydrogen Flammable Gas Hydrogen Selenide Highly Toxic Gas Hydrogen Sulfide Flammable Gas Indium Not Regulated Methane Flammable Gas Molybdenum Hexafluoride
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