How to determine the optimum buffer layer thickness for a solar cells. Is there any specific range for the buffer layer thickness or special equations from which we can calculate the same.
Narendra, according to what I have seen in the literature, buffer layer is usually 25 to 300 nm thick. The thinner it is the better it is. The whole idea is to transmit all the light to the absorber to allow maximum absorption in addition to passivation. The 20.8% efficient CdS based solar cell from NREL has a 25 nm thick CdS layer. However, you may have to vary the thickness in order to optimize the interface proerties, both with absorber and window.
Thanks Ali!!
I know that value ( 25 to 250 nm) from the literature.
I am looking for generalized formula for finding how much thickness is required?
I don't think, there is any general formula for this. But depending on type of solar cells (c-Si, CIGS, organic, perovkite, etc.), the thickness of the buffer layer (BL) varies. However, there are some general thickness ranges for a particular type.
For example, in case of organic solar cells, people use 30-50 nm (Anode BL for regular architecture, cathode BL for inverted architecture) and 1-30 nm (Cathode BL for regular, anode BL for inverted). In case of perovskite solar cells, it's different!
As far as I know, I have never seen any standard equation to find the thickness, however, I would think that you can and it will be a lot of math. That equation will be a function of refractive index of the material, absorption/reflectance, etc. I would suggest you to grow films at various thickness (for example, 30, 50, 70...120 nm) and characterize it as a function of any performance parameter (for example, bandgap, FF/Voc of a solar cell, or crystalline structure). Once you have that data, perform statistics to optimize the thickness.
Hi Narendra
in my opinion there is no magical equation for this problem, the best way of doing it is to use simulation software that are available such as scaps, pc1d , amps,...
you can run the program for different thicknesses values of the buffer then you can see where is the optimized thickness
yours sincerely.
A. Belghachi
If thickness increases or decreases, what is the physics involved in that..
Which parameters are going to effect by varying the thickness.
Dear Bandaru,
If you like, you can investigate the following articles to see the influence of the buffer layer thickness on the photovoltaic performances. In these studies, we have fabricated both the absorber and buffer layer by spray pyrolysis technique. I should say you that, the thickness of the buffer layer is strongly correlated with the processing temperature of buffer layer and the composition and the structure of your absorber layer.
All the best,
Conference Paper Spray Pyrolyzed CIS Thin Film Solar Cells Using Sandwich Str...
Article Non-toxic and environmentally friendly route for preparation...
Dear Narendra,
we cannot have a fixe value but we always we minimize the thickness as much as possible just to create a PN junction, for exemple for CIGS solar cells we take a CdS buffer layer with 100-200 nm thick.
as an example take this articles :
- https://www.sciencedirect.com/science/article/abs/pii/S0925346717303683
good luck.
Check this link on a simulation on the effect of varying TiO2 buffer layer thickness for FTO/TiO2/Sb2S3/P3HT solar cell structure using SCAPS-1D software http://journals.uonbi.ac.ke/index.php/ajps/article/view/1799
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