Quantum efficiency

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This article deals with the term as a measurement of a device's electrical sensitivity to light. In a charge-coupled device (CCD) or other photodetector, it is the ratio between the number of charge carriers collected at either terminal and the number of photons hitting the device's photoreactive surface. As a ratio, QE is dimensionless, but it is closely related to the responsivity, expressed in amps per watt. Since the energy of a photon is inversely proportional to its wavelength, QE is often measured over a range of different wavelengths to characterize a device's efficiency at each photon energy level. For typical semiconductor photodetectors, QE drops to zero for photons whose energy is below the band gap. Photographic film typically has a QE of much less than 10%,[2] while CCDs can have a QE of well over 90% at some wavelengths.

Of solar cells[edit]











Spectral responsivity[edit]

Spectral responsivity is a similar measurement, but it has different units: amperes per watt (A/W); (i.e. how much current comes out of the device per per unit of incident light power). Responsivity is ordinarily specified for monochromatic light (i.e. light of a single wavelength). Both the quantum efficiency and the responsivity are functions of the photons' wavelength (indicated by the subscript λ).

To convert from responsivity (Rλ, in A/W) to QEλ[6] (on a scale 0 to 1):



where = number of electrons produced, = number of photons absorbed.


where t is the measurement time (in seconds), = incident optical power in watts, = optical power absorbed in depletion layer, also in watts.

See also[edit]


  1. ^ Shaheen, Sean (2001). "2.5% efficient organic plastic solar cells". Applied Physics Letters. 78 (6). Bibcode:2001ApPhL..78..841S. doi:10.1063/1.1345834. Retrieved 20 May 2012.
  2. ^ Träger, Frank (2012). Handbook of Lasers and Optics. Berlin Heidelberg: Springer. pp. 601, 603. ISBN 9783642194092.
  3. ^ Silicon nanoparticle film can increase solar cell performance
  4. ^ Delamarre; et al. (2013). "Evaluation of micrometer scale lateral fluctuations of transport properties in CIGS solar cells". Proc. SPIE. 100. doi:10.1117/12.2004323.
  5. ^ A. Delamarre; et al. (2014). "Quantitative luminescence mapping of Cu(In,Ga)Se2 thin-film solar cells". Progress in Photovoltaics. doi:10.1002/pip.2555.