Geometry Analysis of Surface Anti-reflection Structures for Solar Cells
Date Issued
2010
Date
2010
Author(s)
Shih, Chien-Hung
Abstract
Surface texturing is a method to make anti-reflection in solar cells. To form geometric structure on top surface of solar cells by etching can increase number of reflections and reduce reflectivity. In addition, the scale of structure must be several times larger than light wavelength.
In this paper, we analyze two texturing structures of V-groove and upright pyramid array. And we derive analytical formula which can describe number of reflections and optical path. In analyzation we use collimated light to be light source and let rays incident texturing structures normally and obliquely. For oblique incidence on V-groove, we define two conditions according to plane-of-incidence of incident lights which are lying in x-y and y-z plane. Above analyzations we use geometric optics and coordinates transformation of theories. In analytical process, we know that upright pyramid array can be formd by V-groove approximately. This idea let we simplify the analyzations of upright pyramid array.
We also calculate reduct reflectivity from analytical formula. And we compare its solutions with simulation results of TracePro to check the accuracy of analytical formula. We get the results that oblique incidence on V-groove in y-z plane has less reflectivity and it is below 5% as larger tilted angles. Finally, we extend analytical formula to other complex conditions. Like intrinsic silicon which refractive index changes with light wavelength and adding thinfilm on surfaces of texturing structure. We can also get optimal thickness by calculating reflectivity of adding thinfilm.
Subjects
Anti-reflection
solar cells
surface texturing
V-groove
upright pyramid array
Type
thesis
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