Broadband light trapping in nanopatterned thin film amorphous silicon solar cells

AbstractAdvanced light management in thin-film solar cells is important in order to improve the photo-current and, thus, to raise up the conversion efficiencies of the solar cells. In this article two types of periodic structures ¡V one-dimensional diffraction gratings and photonic crystals,are analyzed in the direction of showing their potential for improved light trapping in thin-film silicon solar cells. The anti-reflective effects and enhanced scattering at the gratings with the triangular and rectangular features are studied by means of two-dimensional optical simulations. Simulations of the complete microcrystalline solar cell incorporating the gratings at all interfaces are presented. Critical optical issues to be overcome for achieving the performances of the cells with the optimized randomly textured interfaces are pointed out. Reflectance measurements for the designed 12 layer photonic crystal stack consisting of amorphous silicon nitride and amorphous silicon layers are presented and compared with the simulations. High reflectance (up to 99 %) of the stack is measured for a broad wavelength spectrum. By means of optical simulations the potential for using a simple photonic crystal structure as a back reflector in an amorphous silicon solar cell is demonstrated.

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Enhanced light trapping with double-groove grating in thin-film amorphous silicon solar cells

Optics & Laser Technology ◽

10.1016/j.optlastec.2015.11.021 ◽

2016 ◽

Vol 79 ◽

pp. 95-99 ◽

Cited By ~ 5

Author(s):

Jun Wu

Keyword(s):

Thin Film ◽

Solar Cells ◽

Amorphous Silicon ◽

Light Trapping ◽

Silicon Solar Cells

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Light trapping in amorphous silicon solar cells on plastic substrates

MRS Proceedings ◽

10.1557/proc-769-h6.14 ◽

2003 ◽

Vol 769 ◽

Cited By ~ 2

Author(s):

Vanessa Terrazzoni-Daudrix ◽

Joelle Guillet ◽

Xavier Niquille ◽

Arvind Shah ◽

R. Morf ◽

...

Keyword(s):

Thin Film ◽

Solar Cells ◽

Amorphous Silicon ◽

Theoretical Calculations ◽

Light Trapping ◽

Production Costs ◽

Silicon Solar Cells ◽

Plastic Substrates ◽

Trapping Effect ◽

Thin Film Silicon

AbstractIn order to simultaneously decrease the production costs of thin film silicon solar cells and obtain higher performances, the authors have studied the possibility to increase the light trapping effect within thin film silicon solar cells deposited on flexible plastic substrates. In this context, different nano-structure shapes useable for the back contacts of amorphous silicon solar cells on plastic substrates have been investigated: random textures and gratings.The optimisation of such back reflectors is so far empirical. Gratings constitute a well-known optical technique and their light trapping effect can be optimised by simulation.A first conclusion is that neither the traditional “Haze factor” determined in air for a wavelength of 650nm nor the “rms roughness” of the surfaces are sufficient as criteria to optimise the back contact roughness for light trapping in cells. The shape of grains is a further essential criterion. The authors have so far obtained a relative current enhancement of 16% for solar cells deposited on randomly textured polyethylene terephthalate (PET) as compared to a corresponding conventional solar cell co-deposited on a flat mirror (Ag) on glass. Solar cells on PET with 6.3% stabilized efficiency have until now been obtained. Theoretical calculations indicate that gratings can enhance the current of a-Si solar cells by up to 30 percent.

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