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What role do phosphorus and boron play in crystalline silicon solar cells?
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solar cell
A commonly used solar cell structure. In many such cells, the absorber layer and the back junction layer are both made of the same material.
In crystalline silicon solar cells, phosphorus and boron act as dopants—impurities deliberately added to the silicon lattice to modify its electrical conductivity and create the necessary electronic structure for power generation.12
- Phosphorus: As an element with five valence electrons, phosphorus acts as a donor atom when added to the silicon lattice. It provides an extra electron that becomes available for electrical conduction, creating n-type (negative) semiconductor material.13
- Boron: As an element with only three valence electrons, boron acts as an acceptor atom. By substituting for a silicon atom, it creates a positively charged site known as a hole. This results in p-type (positive) semiconductor material.13
The fundamental operation of a solar cell relies on the p-n junction formed by joining these two dissimilar materials. When sunlight strikes the cell, the absorbed energy excites electrons, allowing them and the holes to move across this junction. This movement creates an electric current, enabling the conversion of light into usable electricity.23