Thesis defence S.H. Ahmadpanahi: solar cells

16 September 2019 12:30 - Location: Aula, TU Delft - By: webredactie

Light trapping in Si thin film solar cells. Promotor 1: Prof.dr. M. Zeman (EWI); Promotor 2: Dr. O. Isabella (EWI).

This thesis is focused on a deeper understanding of light behavior inside a periodically textured Si film. The result of the thesis, however, is not limited to solar cell application and can be used to understand the light behaviour in any periodic textured thin film. Introducing a semi analytical approach to calculate the contribution of each resonance in total absorption is one of the achievements of this thesis. The optical thickness of a grating structure largely depends on the grating properties such as height, duty cycle and grating profile. For a wavelength-scale structure, it is even more challenging to define one optical thickness for all diffraction orders. In the method we have proposed, tracking of guided modes is possible without knowing the optical thickness or the dispersion diagram of the grating structure. In this work a semi-analytical approach is introduced to calculate the contribution of guided and non-guided resonances to total absorption of a grating waveguide structure under normal and oblique incidence. In this approach, we use Fourier expansion to calculate the energy spectral density of the electric field inside the absorber. The thesis also focus on calculating the maximum absorption enhancement achieved by each type of resonance in a waveguide structure with symmetric and asymmetric gratings. In this chapter a different approach is introduced to count the number of resonances in a grating waveguide structure, at each frequency. Then, temporal coupled mode theory is used to calculate the maximum absorption enhancement for each diffraction order. This approach is extended for a thin film with double-side texturing.

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For access to theses by the PhD students you can have a look in TU Delft Repository, the digital storage of publications of TU Delft. Theses will be available within a few weeks after the actual thesis defence.