Kindly explain how should I Fabricate cell.
What I do is
1. Taking Mo coated glass slide and protect corners using polyamide tape during spin coating of czts.
2. After spin coating polyamide tape is removed and sample is annealed at 550 I'm h2s. (may be problem starts here. Since the part protected by tape now loses conductivity during h2s annealing)
3. Than I deposit cds, Zno and Al:zno after protecting the back contact again with polyamide tape (temperature sustainability upto 250C).
4. Finally I take IV between Mo and Azo. I am not making grids and to improve voc scribe the cells into smaller area cells.
My jsc and voc is coming good but fill factor is below 30 what should I do?
What is the standard way to protect back contact?
Dear Jan-Martin
I have attached here the IV plot. Kindly look into this
Strange -- are these different slopes (between the dark and the illuminated curve) real? Please make sure that it's not a data plotting artefact (different y-axis scales).
Two more questions: How do the curves look like for stronger negative voltages -- is there a limiting value for the current? How does the illuminated curve look like (over the extended voltage range) if the illumination is half the intensity (compared to the present one)?
I need to see these points. Usually i do not go for large negative voltage to prevent any breakdown.for different intensity i need to perform the measurement. Kindly suggest some references for deeper insight to these questions.
With the question related to stronger negative voltage I intend to find out two things: (a) Is there a significant shunting contribution? (b) What is the true maximum photocurrent? However, the latter can only be answered easily if there is no shunting present.
With the question about a current--voltage curve for half the illumination intensity I intend to find out whether there is some spurious photoconductance effect present; this would be most likely the case if the slope for positive voltages depends on the illumination intensity.
Dear Jan-Martin
I have tested several now several times but the slopes are coming different in dark and light characteristics. what is the possible reason. Can it be associated with excited trap states that may be coming into observation
Reduction of fill factor may generally originate from the series resistance of your solar cell
this could be due to the Mo/CZTS contact , CZTS , CdS layers resistivity and the different interfaces quality
try to avoid using a plolymer mask that could be a contamination source , use for example simply a glass slide to cover the Mo electrode.
Are you able to vary the doping level of the light-absorbing and of the current-conducting layers? If so, what result for the dark curve do you get for higher doping?
Furthermore, were you able to measure the current for larger negative voltages without destroying the device? If so, what result for the illuminated curve do you get with respect to possible shunting or photocurrent extraction?
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