Another viewpoint. The spectral response (QE) is usually measured with low intensity probe light using chopped light from a monochrometer, and a lock-in amplifier. This gives a "dark" spectral response. The same measurement can also be done under constant auxiliary bias illumination (e.g. AM1.5) in which case the trap occupation and the Fermi levels will be different, and the QE will be different. The differences between light and dark SR are generally larger for cells with more complex recombination pathways (e.g., CdTe-based or a-Si:H) than for single-crystal Si devices. Also there may be time dependent phenomena.

In simulations (AMPS, SCAPS, etc.) one has the option of setting the spectrum and intensity of the bias light (as well as the intensity of the QE measurement light) and one sees substantial differences between light and dark SR.

The spectral Response of the solar cell is very important parameter which determine the range of utilization of solar cell from the whole spectrum of solar radiation which covered the range (300-2200 nm) UV, Visible and near infrared region which depends mainly on the type of solar cell material , for example the conventional solar cell which manufactured from Silicon , it detect only (300-1100 nm) but by using another material u can get more efficiency like tandom solar cell which manufactured from GaAs material (multi Junction), which detects wide range (300-2000nm) with efficiency exceed than 40%

Dear Dr. Naseer K. Kasim

Thank you for your reply.

My question is regarding Dark spectral response but not illuminated spectral response.

Please find the dark spectral response spectra in the attached figure.

Reference: Amorphous and‘micromorph’ silicon tandem cells with high open-circuit voltage. "Solar Energy Materials & Solar Cells" 87 (2005) 251–259.

Dear Mr Madaka,

welcome,

External spectral quantum efficiency is defined as the the collected photogenerated current at a wavelength interval dlamda due to the the incident photon flux in the wavelength interval dlambda with a light wavelength lambda.

So, the quantum efficiency is associated with the incident light. Drk means no light. If you intend the invisible solar radiation then one can define a dark(invisible) EQE.

But i think you intend the response of the base(back) cell which is covered by the window or the top cell when two cells are connected in tandem. The back cell will be in dark due to the front cell. The front cell absorbs the incident solar radiation in its absorption range and let the rest passing to the back cell which can be named dark cell as it resides in darkness.

This is what indicated in the figure above where the uc cell wich is the bottom cell

Has the the continuous line EQE when it is under the top cell and has the dotted curve above it when it is directly illuminated.

Best wishes

Thank you Prof. Abdelhalim Zekry for your valuable answer.

Another viewpoint. The spectral response (QE) is usually measured with low intensity probe light using chopped light from a monochrometer, and a lock-in amplifier. This gives a "dark" spectral response. The same measurement can also be done under constant auxiliary bias illumination (e.g. AM1.5) in which case the trap occupation and the Fermi levels will be different, and the QE will be different. The differences between light and dark SR are generally larger for cells with more complex recombination pathways (e.g., CdTe-based or a-Si:H) than for single-crystal Si devices. Also there may be time dependent phenomena.

In simulations (AMPS, SCAPS, etc.) one has the option of setting the spectrum and intensity of the bias light (as well as the intensity of the QE measurement light) and one sees substantial differences between light and dark SR.

More precisely, the dark QE is the limiting QE as the probe beam intensity is reduced towards zero.