Any energy above the band gap energy is not utilized by the solar cell and instead goes to heating the solar cell. At these wavelengths, each photon has a large energy, and hence the ratio of photons to power is reduced. However, unlike the square shape of QE curves, the spectral response decreases at small photon wavelengths. This limit is the same as that encountered in quantum efficiency curves. The ideal spectral response is limited at long wavelengths by the inability of the semiconductor to absorb photons with energies below the band gap. Silicon is an indirect band gap semiconductor so there is not a sharp cut off at the wavelength corresponding to the band gap (E g = 1.12 eV). At long wavelengths the response fall back to zero. At intermediate wavelengths the cell approaches the ideal. At short wavelengths below 400 nm the glass absorbs most of the light and the cell response is very low. The spectral response of a silicon solar cell under glass. A spectral response curve is shown below. The quantum efficiency gives the number of electrons output by the solar cell compared to the number of photons incident on the device, while the spectral response is the ratio of the current generated by the solar cell to the power incident on the solar cell. ![]() The spectral response is conceptually similar to the quantum efficiency.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |