This illustration shows how silver contacts form on silicon solar cells. a) Each contact starts as a glass paste that contains small silver particles (black) and lead oxide. As the temperature rises quickly during manufacturing, the glass paste melts, releasing lead ions that etch away the silicon’s anti-reflective coating. b) At higher temperatures, silver ions migrate through the molten glass and deposit on the underlying silicon. c) Once cooled, the finished contact contains solid silver blobs that have been squeezed together by heat; tiny silver particles within the paste, which is now solid glass; and solid silver on the silicon surface. All three types of silver are needed to make the contact effective.
Credit: SLAC National Accelerator Laboratory
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