I have repeated my experiments several times, and tried my level best. But Jsc measured from solar cells is 25.2 mA/cm2 while Jsc calculated from EQE is 19.50 mA/cm2. This is a big difference. How can it be explained or justified? What may be possible error or correction? The device is based on PEDOT:PSS/2D-3D Perovskite/ PCBM/BCP/Ag. Please provide me a sufficient answer.
Dear Gul,
welcome
I think the difference may lay in the incident solar radiation. It must be well known. Its spectral irradiance must be accurately known. You must revise it elaborately. The second factor that affect the deviation is the discretization of the wavelength range. As the the discerization gets finer, the results will more accurate.
Best wishes
Dear Gul,
welcome
I think the difference may lay in the incident solar radiation. It must be well known. Its spectral irradiance must be accurately known. You must revise it elaborately. The second factor that affect the deviation is the discretization of the wavelength range. As the the discerization gets finer, the results will more accurate.
Best wishes
Abdelhalim abdelnaby Zekry Respected Prof. I am grateful to you for your time and concern. Sir, I have repeated my experiment several times, and instruments is working finely. Except this study, all results are fine. Can these results be acceptable in this form?
DearMuhammad,
which study?? Do you mean the calculated short circuit current. and the measured short circuit current.
On question which is very important is the source used in the two measurements is the same. I am almost certain that the difference is due to the input solar radiation. This is the quantity which is not measured in the experiment.
Best wishes
Abdelhalim abdelnaby Zekry Sir, I understand the problem is with the incident radiation. I just meant that were these results acceptable to be published? or I should repeat the experiment? I need your kind guidance and suggestion.
Muhammad,
Please try to concentrate and answer my question. Do you know certainly the spectrum of the incident solar radiation while measuring the EQE.
If you do not need to validate Isc and make a comparison with the that extracted from the I-V curve which is measured under sayAM1.5. Then you can consider that you have two curves but not necessarily they are related in the sense you try to prove.
It is not that you repeat your experiment, you have to define your incident radiation sources in the two cases. Otherwise the spectral response of the solar cell tell you information about its response to the different wavelengths.
I do not understand why do you insist to relate the short circuit current in from the I-V curve and the spectral response curve?
They are only elated in case of the same incident solar radiation.
Best wishes
if your cell is very small or not aligned to the QE beam it is possible that part of the beam is outside the cell which will make measured QE and QE-Jsc incorrectly low. Is cell area measured correctly for IV-Jsc calculation? Incorrect simulator calibration is another possible issue.
If the difference persists after everything is aligned and calibrated, then it can be due to photogeneration difference in a regular Jsc measurement and in EQE measurement. 1sun photogeneration in a regular Jsc measurement could improve the charge collection by reducing recombination (either by saturating SRH centers or by changing the distribution of electrochemical potentials). To verify this, one needs to compare dark QE (with no background illumination) and light QE (with 1sun background illumination and SC conditions). I'd not suggest publishing the results without figuring out the source of difference (experimental errors or real physical effect).
@Dmirty Krasikov Dear Fellow, thank you for your time and a very satifying answer. Can you please share any reference paper or book? I'll be highly grateful to you for this favour.
I am not aware about a comprehensive reference covering all possible effects. Info on QE measurements can be found in books on solar cell characterization, e.g. Advanced Characterization Techniques for Thin Film Solar Cells,2011 WILEY-VCH. One effect of photoconductivity of buffer layer on QE is described in dissertation T.J Nagle "Quantum efficiency as a device-physics interpretation tool for thin-film solar cells" and paper Gloeckler,Sites, Journal of Applied Physics 95, 4438 (2004). There could be other effects.
From the common sense, if you have difference in collection under background light vs dark, you have either photogeneration-dependent doping in either of active layers or interfaces or photogeneration-dependent states of recombination centers. You will not be able to quickly figure out the exact mechanism without a lot of modeling and additional experiments, but you may check whether you have in principle any photogeneration-dependent collection by comparing the dark and light QE measurements.
A possible contribution to this error can occur due to the strong frequency-dependence of the EQE for perovskite solar cells, especially at low frequencies. So if your measurement of Jsc involves a different frequency (or steady state) compared to the EQE measurement chopper or perturbation frequency, you can have a disparity. For more details, please see https://pubs.acs.org/doi/abs/10.1021/acs.jpclett.8b01245.
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