Dear All,
I have been working on various light trapping techniques for the a-Si thin film solar cells.
Recently, I came across a case of wet chemical textured Glass (high etching depth:>5 um, hazy surface) substrate.
When we measured the optical transmittance (Total, Parallel, Diffused) of samples by the equipment (Haze Master-Scinco). We see that the samples with high etching depth and hazy surface showed almost similar total and diffused transmittance. i.e Haze ratio: ~100. Is it possible for a sample to have 100% haze ratio...? I am surprised of it....Can any expert please guide me...
In several research paper like from Konagai et. al and few other they used index matching solution to measure the optical (TT,DT) properties of such samples...We also used the index matching (CH2I2, n=1.74) solution in several case....But those results are different from the normal results without index matching solution...Can anyone please guide...which method is better...
Reference: http://www.sciencedirect.com/science/article/pii/S0042207X15001396
Thanks
Yes. It is possible. However, you will need to consider your solar cell deposition on a textured surface. Based on my experience with 100 GaAs surface, you will have somewhat porous and non even film thickness.
Thanks a lot Onno Gabriel and K. A Pandelisev for your useful answers.
I have question from Onno Gabriel.
So It means for such high haze related films, index matching solution CH2I2 should be used for the measurement of TT and Ref. (In case of AZO films)...
IEC standard 62805-1 describes the total haze as "ratio of the scattered flux of light to the total flux of light transmitted through the PV glass in the wavelength range 300 nm to 1250 nm, the direction of the scattered light deviates more than 2,5° from the direction of the incident beam " . 100% haze means that no light in the 300 to 1250 nm range passes through a 2.5 degree cone will pass through the sample.
You should keep in mind that Haze value are always measured in far field. Large structures may scatter strongly in far field but are useless for light trapping in thin films, like aSi cells.
For the glass that you mention with high etch depth >5um this could be the case. Check the feature size of the scattering interface.
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