I got the following Nyquist plot, measured in a frequency range of 100Hz - 1MHz by an Waynkerr LCR meter. I am trying to model an equivalent circuit for it and tried a lot using CPE also, but not able to fit correctly. The X and Y axis are in Ohm
Is it because that the sample has very low value of Z' and Z''?
Dear Bipul,
I worked on the impedance spectroscopy for solar cells in the forward biasing to determine its physical parameters.The shape of the of the polar impedance you have may be due to an equivalent network composed of of two RC parallel circuits in series with a series resistance Rs.. Your circuit will contain five elements R1 C1 IN PARALLEL connected in series with a other R2C2 in parallel connected in series with a series resistance Rs. The time constant R1C1 > R2C2 as apparent from separate peaks. The R1C1 network is due to the marterial and the R2C2 is due to the metallic contacts to the materials.
Please try and return to me.
Thanks Zekry Sir. I tried a lot to model the equivalent circuit considering your suggestions. I had tried taking different parallel combination of C, R and CPE. I considered CPE as the semicircles were not perfect but somewhat depressed. But I could not fit the Nyquist plot at all.
Dear Bipul,
I would like that you interact with me more rapid than that. You 8 days to replay on my comment. Any how. It seems for me that reactive part is smaller than half of the resistance span of the semicircles as i see from your impedance plot. to account for that you have to a shunting capacitance on the the two RC circuits. I am sure this will will work well. Please tell me!
sorry sir. I tried it according your suggestions, still not fitted. For the shunting capacitor, I used the following equivalent circuit code in Zsimpwin:
1) (C((CR)(CR)))
2) For other options I tried adding parallely extra CPE to both the parallel circuit.
(CQR)(CQR)
would you please display the the proposed equivalent circuit.
You can solve the problem at first by drawing the semicircles.
This is not what i told you:
please connect R in series with R in parallel with C an series with an other R in parallel with C and shunt the two RC circuits by an other capacitor C.Please draw this circuit and shoe it to me.
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