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| A magnesium salt may reduce the hazards and costs of making thin-film photovoltaic devices |
Substituting magnesium chloride for toxic cadmium chloride could free cadmium-telluride solar-cell manufacturers from a costly and hazardous process without sacrificing efficiency, according to a new study.
At the heart of a standard CdTe solar cell is a photovoltaic junction formed by the interface between neighboring thin layers of CdS and CdTe. Without processing the layers after deposition, a cell converts incident solar power into electric power with less than 5% efficiency. Manufacturers bump this up to between 10 and 20% using a junction activation step.
For more than two decades, activation has relied on CdCl2, usually deposited as a thin coating on the cell’s CdTe layer. When the cell is heated, chloride diffuses through its stacked structure and reforms the physical and electronic characteristics of the cadmium-containing layers, leaving a more efficient photovoltaic junction.
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