Fabrication of thin crystalline silicon solar cells with advanced light trapping

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2017
Hadibrata, Wisnu
Thin crystalline silicon (c-Si) solar cells with thickness in the order of few tens of microns offer many attractive applications, such as, electronic wearables, space probes and satellites thanks to their flexibility and light-weight character. However, reducing the thickness of active layer of silicon solar cells leads to poor light absorption within the silicon layer, especially in the near infrared region of the solar spectrum. The poor absorption becomes problematic for thin c-Si solar cells as it causes substantial photocurrent loss. One method to curtail the absorption loss is to incorporate light trapping structures into thin silicon. Light trapping structure of random upright pyramids has been proved efficient for conventional silicon solar cells allowing for easy and inexpensive method of texturization by alkaline-based solution. However, the average size of the randomized pyramids ranges from 4 - 10 µm which is not suitable geometry for thin silicon with thicknesses less than 20 µm. Recently, periodic submicron inverted pyramids have been shown to enhance absorption in thin c-Si solar cells. In this work, we fabricated flexible thin c-Si solar cells with advanced light trapping of periodic inverted pyramids using relatively low-cost wet etching process as well as optimized random upright pyramids with maximum size of 2 µm for thin silicon. Efficiencies of 10.01% and 13.6% have been achieved for planar and textured silicon solar cells with a thickness of 30 µm, respectively. Thin c-Si solar cells were successfully attached to a polymer and removed from the initial wafer. In this thesis, we will discuss the fabrication process of flexible thin c-Si solar cells along with the fabrication of the advanced light trapping structures. 

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Citation Formats
W. Hadibrata, “Fabrication of thin crystalline silicon solar cells with advanced light trapping,” M.S. - Master of Science, Middle East Technical University, 2017.