The thickness of the intrinsic layer is about 25 micron. I would also want to know that how should I decide thickness and choice of electrode material for the aforesaid cell.
Dear Ankit,
welcome!
What is the type of the crystal structure of the silicon material? is it amorphous ? or poycrystalline or crystalline? The thickness of the i-layer depends on the degree of crystallinity of the material.
However, there is some basic principles governing the the thickness of the i-layer.
Since the i-layer must be the major optical absorption layer, then
Its thickness must be equal or greater the penetration depth of longest wavelength of the incident solar radiation,
The other structural condition of the i-layer, is that the thickness must be smaller than the diffusion length of the minority carriers,
The thickness of the p an n emitter layer must be smaller than the diffusion length of minority carriers in these regions.
P-N diode structures are preferred for crystalline and senicrysatlline silicon while
pin diode structure is preferred for amorphous hydrogenated silicon.
Amorphous silicon has very different optical and electronic properties from C-Si.
Less than one micrometer of a-Si:H is sufficient to absorb an appreciable portion of the incident solar radiation. So, there is no need for 40 um thickness. Accordingly,40 micrometer thick layer can be classified as thick film and not thin film The p and n emitter layers are much thinner than one micrometer.
For more information please see the link: https://ocw.tudelft.nl/wp-content/uploads/Solar-Cells-R5-CH7_Thin_film_Si_solar_cells.pdf
Best wishes
Dear Sir
Thank you for your answer. My material is poly (nano)crystalline Si. I have developed the cells from powders so it is rather difficult to control the thickness of material to
Dear Ankit,
What is the initial doping of Si powder? The optimum doping for C-Si p-n cell is about 1x10^17 /cm^3. If you have relatively thick fine grained Si you may use better p-n junction structure,
After producing the p-n junction solar cell in order to measure the minority carrier lifetime you can use the well known method of the open circuit voltage decay where you keep the solar cell in dark, forward bias it and interrupt the current and observe the decay of the open circuit voltage with time. by evaluating the slope of the voltage decay with time one can determine the minority carrier lifetime.
Just by measuring the dark i-v characteristics , and calculating the reverse saturation current I0, one can predict how good the junction diode is. If I0 is small and approaching that of the single crystal solar cell, means that the minority lifetime is no too small.
For details of measuring the open circuit voltage decay please refer to the link:https://www.researchgate.net/publication/232710923_A_Zekry_and_G_El-Dllal_effect_of_MS_contact_on_the_electrical_behavior_of_solar_cells_Journal_of_solid-state_Electronics_Vol31_No1_1988
best wishes
Article A. Zekry and G. El-Dllal, “ effect of MS contact on the elec...
Dear Sir,
The doping was of the order of 10 ^ 17 cm ^3 as you said is optimum for c-Si PN cell. I will try the method suggested by you.
Dear Ankit,
You can go directly for measuring the short circuit current , it is also an indicator of the recombination rate and therefore the the quality of the substrate material. So, if the short circuit current gets closer to that of the standard c-Si solar cells for the same illumination intensity, then the material is suitable for solar cell applications.
I expect that the minority carrier lifetime will be much smaller because of the grain boundaries.
Please it is good if you report about your experiments
Best wishes
Dear Sir,
Thank you for your guidance. I tried once roughly and was able to get 6-7 microampere Jsc. however, I used intrinsic layer too in there and thickness of cell was also not known to me at that time. The sintering and annealing were not done properly too. I will try this very soon. The doping process established was reported as below:
https://link.springer.com/article/10.1007/s10854-017-7340-5
There is another possibility for classification: For me it is most relevant that there is a different working principle behind "silicon bulk" and "silicon thin film" cells. The photo-current of "bulk" cells is essentially diffusion-driven (light absorption mainly in the field-free bulk), whereas that of "thin film" cells is field-driven (light absorption mainly in the field region).
Therefore, I would consider yours to be a "thick thin-film cell". ;-)
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