Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Science - Department of laser application in engineering

Bibliography: p. 207-192.

Conventional energy sources such as natural gas, oil, coal, or nuclear are limited and highly depleted. Today, energy based on {u201E}green{u201F} resources has attracted considerable interest and investment worldwide, as a viable alternative to the use of polluting fossil fuels. Solar energy is the most abundant source of such {u201E}green{u201F} renewable energy, coming in its two forms: light and heat. The photovoltaic (PV) solar cell (SC) is one of the predominant solar energy harvesting devices to convert light directly to electricity. Currently, bulk crystalline silicon (C-Si) photovoltaic modules have ~90 % of the global PV market. Silicon (Si) is one of the largest broadband light absorbing materials, where the power conversion efficiency (PCE) of a planar C-Si SC reaches 22 %. However, C-Si SC suffers from high cost. The second generation SC technology, based on low-purity thin-film (TF) materials, has emerged to reduce the high cost of the traditional C-Si SC and yet, the conversion efficiency is only ~12 %, due to the small optical path length. The third generation of solar cell technology has improved the light absorption in TF-SC using light trapping techniques. This approach increases the optical path length and promotes the generation of e-h carriers, which elevates the efficiency of TF SCs. Consequently, an efficient TF SC can be designed using less active material with reduced cost. Nanowires (NW) are highly promising nanostructures that have unique optical and electrical characteristics compared to TF SCs. Such NWs have a number of merits, such as reduction in reflection, improvement in trapping, and consumption of less material

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