Currently, I am working on Iron di-silicide (FeSi2) material for application as active absorber in solar cell. Based on simulation data, I found a high value for short circuit current density, Jsc which is ≥ 50 mA/cm2 produced from a single heterojunction solar cell made of FeSi2 absorber. Unfortunately, the designed heterojunction cell lacks of low photo-generated voltages (Voc) remaining at less than 500 mV due to the low band energy gap of ~0.85 eV.
All the simulation input data were feasible. In fact, I think generation of this high current is reasonable due to the high absorption coefficients that FeSi2 material owns. I found that FeSi2 material has higher absorption probabilities (and coefficients) over visible and IR spectra than any other absorber used in solar cells now-a-days. For instance, at 300 nm wavelength (λ), value for absorption coefficient (α) is ~6×105 cm-1 and at 1500 nm λ, α is still as high as 6×103 cm-1. Consequently, 1-2 µm thick FeSi2 can absorb most of the incident photons.
However, other than high absorption coefficients, which factors are responsible for this high photo-generated current?
Welcome Mahbub,
As the band gap is relatively low the open circuit voltage will be also low as the open circuit voltage is a fraction of the bandgap of about .6Eg in eV.
As for the current it is expected that the short circuit current will be relatively large as the absorber is sensitive to a larger portion of the incident solar ordination starting from photon energy =Eg =0.8 eV.
This shortcircuit current will be obtained at negligible recombination loss of the photogenrated current meaning that you assumed relatively large lifetime and inteface sate density at the heterojunction.
Also the dark current will be relatively small because of the above assumptions.
I would like that you see the paper in the link: Article M. Abdelnaby, A. Zekry, F. Elakkad and H. F. Ragaie, “ Depen...
If you give the material parameters i can verify your sinulations
Best wishes
https://www.hindawi.com/journals/jen/2014/946406/
Article Analysis of Si/SiGe Heterostructure Solar Cell
You did not give much information to discover the cause of the high short circuit current in your cells. Is this value of shortcircuit a measured or simulated current? What is the structure of your cell.
After giving more details i will give an answer to your question.
Best wishes
Abdelhalim Zekry sir,
It was a simulation yielding.
Structure:
BSF(p+ BaSi2, 0.1 um) /absorber(p-FeSi2, 2 um) / window (n- CdS, 50 nm) /TCO (n+ FTO, 50 nm)
Welcome Mahbub,
As the band gap is relatively low the open circuit voltage will be also low as the open circuit voltage is a fraction of the bandgap of about .6Eg in eV.
As for the current it is expected that the short circuit current will be relatively large as the absorber is sensitive to a larger portion of the incident solar ordination starting from photon energy =Eg =0.8 eV.
This shortcircuit current will be obtained at negligible recombination loss of the photogenrated current meaning that you assumed relatively large lifetime and inteface sate density at the heterojunction.
Also the dark current will be relatively small because of the above assumptions.
I would like that you see the paper in the link: Article M. Abdelnaby, A. Zekry, F. Elakkad and H. F. Ragaie, “ Depen...
If you give the material parameters i can verify your sinulations
Best wishes
Hello Md. Mahabub Alam Moon,
You may want to have a look at the supplementary material of the following paper.
Article Device Engineering of Perovskite Solar Cells to Achieve Near...
The graphs between bandgap of the active layers vs Jsc, Voc, FF, and efficiency under detailed balance limit has been plotted in the said document.
Please not that any additional recombination will affect the performance metrics. Moreover, FF and Voc are the most affected parameters with the recombination.
I hope the information will be helpful to you.
Best regards
Sumanshu
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