Dear Sreeja

Quantum efficiency is a term intrinsic to the light absorbing material and not the cell as a whole; it refers to the percentage of absorbed photons that produce electron-hole pairs. Whereas energy conversion efficiency, is the percentage of incident electromagnetic radiation that is converted to electrical power, when a solar cell is connected to an electrical circuit. This overall efficiency depends on many factors including the temperature, amount of incident radiation and the surface area of the solar cell [1].

        The IQE  represented internal quantum efficiency that the ratio of generated charges as a result the absorbed photons, therefore always IQE greater than external quantum efficiency ( EQE). Because the IQE  equal EQE  divided on ratio of absorbed photons [[i]]:

 IQE=EQE/A(cut off)

Where EQE  is external quantum efficiency, A(cut off) is absorbance at wavelength (cat off).

[1]Zweibel K., and Hersch P., "Basic photovoltaic principles and methods", New York, Van Nostrand Reinhold, 1984.

[i]Yingchi Liu," Optical Profile and Nanostructure Effects in the Charge Carrier Transport and Performance of Photovoltaic Devices", Thesis of PhD, Department of Physics and Astronomy, University of North Carolina, 2013.

 With best regards

Thank you for your answer. I'm aware that both the efficiencies represent different aspects. 

However, my question is - In an EQE measurement, at every wavelength of light that is made incident, the DSSC give a certain current, voltage and efficiency right ?(%EQE is calculated from the current produced by the whole cell at each wavelength). So if this is integrated over the whole wavelength range, shouldn't it be approximately same as the Power conversion efficiency obtained from I-V graphs got using the solar simulator?

Dear Sreeja

You can perform EQE on a biased cell (just like PCE).  Under identical conditions (i.e. similar incident light spectra at the two setups), power conversion efficiency can be obtained via EQE which also reads the PCE (by sun simulator) result.

Please find the attachment for more details.

You may also  refer to :

https://www.researchgate.net/publication/301830518_Local_collection_efficiency_in_the_nano-crystalline_solar_cells

Article Local collection efficiency in the nano-crystalline solar cells

Thank you very much.

Dear Sreega,

Adding to the colleagues above, If you have the external quantum efficiency of a solar cell it means that you have the the photo current  dIp(lambda) of the cell at the intended wavelength lambda and a wavelength interval dlambda divided by the incident photo flux F= I(lambda) dlambda/ Ep, with I is is the irradiance power at the wavelength lambda and wavelength  interval dlambda per cm^2 per and Ep is the photon enrgy Ep=hC/lambda, C is the spped of light and h is the Planck constant.

So, the external quantum efficiency is not the photoconversion efficiency since the PCE= iph x Voc x FF/ incident solar power

The photo current can be calculated from the external quantum efficiency by 

Iph= integral EQEX F over all wave length intervals of the incident solar radiation

     = integral (EQEX Ix dlambda/ Eph),

Knowing Is the reverse saturation current and the ideality factor, the series resistance and the shunt resistance one can calculate an illuminated i-v curve. From which one can get Voc, and the fill factor. One can calculate also the incident solar radiation by integrating the irradiance curve. If one uses AM1, the input power is 100 watt.

I think this is an outline of the whole picture of the solar cell papremeters.

Best wishes

Thank you very much sir, for your answer.

Hi there,

External Quantum Efficiency (EQE) for a photovoltaic device is the ratio of extracted free charge carriers to incident photons. This ratio is obtained by measuring the photocurrent spectrum of the photovoltaic device under test and comparing it to the photocurrent spectrum of a calibrated reference photodetector, thereby removing the spectral characteristics of the test system. Very important link to more information, http://photonicswiki.org/index.php?title=External_quantum_efficiency.

Regards,