I am simulating perovskite solar cell wherein i am changing the thickness of absorber layer from 0.6 to 2 um to see its effect on different performance parameters of the device.
Kindly suggest if this range of sweep is acceptable? Can we go upto 2um?
Dear Romana Yousuf ,
Basically the thickness of the absorber layer is dictated by the absorption depth of incident solar radiation which is equal to 1/alpha where alpha is the absorption coefficient. Since the alpha is smallest at the longest light wavelength then when calculating the thickness d required, one applies the rule:
d= 1/alpha smallest at the longest absorbed wavelength.
It is not recommended to increase the thickness of the absorber beyond this thickness because of the following:
- One has to keep the thickness as small as possible for lowest cost.
- As the thickness increases one has to make the diffusion length L of the carriers at least equal to the thickness of the absorber d.
Since L= sqrt DT where D is the diffusion coefficient and T is the lifetime of the carriers.
As one increases L then one has to increase both D and T which requires less defective material.
Quantitatively you must start scanning from 100 nm to about one micrometer.
You will find a peak value for the PCE at a specific d, this will be the best thickness.
Best wishes
As Abdelhalim abdelnaby Zekry Sir already nicely explained, depending on the absorption pattern of the pervoskite material (alpha), bulk defect density ( deciding the value of minority carrier life time, tau) and carrier mobility (mu), a typical perovskite material should give its best efficiency for the absorber thickness in the range of few hundred nanometers, above which it will decrease continuously. Hence, there should hardly be any point to simulate it upto 2micrometter. I do agree with Abdelhalim abdelnaby Zekry Sir, upto 1-1.5 um should be sufficient.
Thank you all for your kind responses and suggestions....
I would like to add here that i have taken the defect density as 1^12/cm3. At this defect density, i calculated the diffusion length that came out to approximately equal to 16um. Then further, at the same defect density, i simulated the device for different absorber thickness where i found that max efficiency is produced at the absorber thickness of 8um.
But the values are too large. Can you pls correct me??? Where exactly i m wrong so that i m getting such large values??? Do i need to increase the defect density in my simulations???
Pls help me....
Thanks
Regards
Dear Romana Yousuf ,
Welcome again,
If the diffusion length is large then the absorber thickness will be limited by the absorption coefficient. Then please tell us what is your alpha?
Best wishes
Thank you again Abdelhalim abdelnaby Zekry sir,
I have downloaded the refractive index data of MAPbI3 from "refractiveidex.info". then made it compatible with the units of ".abs file" of SCAPS and put the same in the absorption folder of SCAPS so that the material can absorb the solar radiations according to that graph.
according to the details provided by the "refractiveindex.info", α = 81448 cm-1
Regards
Can You tell me please, how can i select wavelength range to make abs. file for any layer of solar cell optimization??
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