Functional Green Nanomaterials Designing Approach to Spectroscopic Evaluation
Ahmed Emad,a b Irene S. Fahim,a b and Tawfik Ismaila c
a School of Engineering and Applied Sciences, Nile University, Sheikh Zayed, Giza, Egypt
bEngineering Systems Research Center, Nile University, Sheikh Zayed, Giza, Egypt
c Wireless Intelligent Networks Center, Nile University, Sheikh Zayed, Giza, Egypt
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The challenges of producing clean energy while preserving our environment have been an objective that is being actively pursued around the world. Developing a way to produce clean energy from the sun is one of the most promising approaches. However, while there is a plethora of activities in the solar cell area there seems to be much less activity in related areas that will make it possible to reduce the overall cost of delivering energy and improve system efficiency through using green materials. The incorporation of a natural nanopolymeric layer to replace the conventional polymeric top layer will be introduced in this study. This nanolayer will enhance the electrical and absorption properties of the solar cell.
Nanomaterials for Spectroscopic Applications Edited by Kaushik Pal
Copyright © 2021 Jenny Stanford Publishing Pte. Ltd.
ISBN 978-981-4877-69-5 (Hardcover), 978-1-003-16033-5 (eBook) www.jennystanford.com
Introduction
Nowadays, countries face a significant obstacle in supplying large amounts of energy from non-renewable sources due to the enormous increase in energy demand. China produces 30% carbon dioxide emissions, followed by the United States with 15% based on 2010 statistics [1]. The fact that controlling carbon emissions is a very tough issue. The contribution of carbon emissions by fossil fuels has increased by about 90% from 1990 to 2010. Carbon emissions are affected by several means as an industry, transportation, and heat production. Fossil fuels contribute to 21% of the total greenhouse gas emissions besides burning coal, transportation, and industiy [2]. Consequently, the scope of energy harvesting has been shifted in the last decades from non-renewable energy to renewable energy. The large amounts of pollutants produced from different industries pushed recent studies to look for smart solutions. Utilizing solar energy is one of the most promising approaches for one of the cleanest energy sources. Since exploitation of light without transforming it into different forms is considered a passive technology, recent research tries to utilize solar energy and convert it into electricity.
A study held in 2007 shows the effectiveness of solar cells to suffice the world’s consumption of electricity. Four percent of the surface area of the land would be enough to supply the world's usage of electricity. For example, less than 1% of European land would serve all the continent and supply the energy required for all the countries [3]. The use of solar cells has improved from
1.4 GW to 40 GW within 10 years, only from 2000 to 2010. This increase addresses the interest in countries to head to solar energy. Germany, the United States, and China have led the evolution of these numbers throughout the last years. China had a significant contribution to the photovoltaics industiy, with 32.3% of total solar cells capacity worldwide. As per 2018 statistics, the United States and Germany share 11.5% and 8.3%, respectively [4]. In Europe, solar energy contributes to 4% of the electricity of the total continent consumption. Solar energy resources contribute to over 7% of the electricity generated in Germany, Italy, and Greece. In the worst-case scenario, it is predicted that at least 10% of the electricity needs in Europe will be provided via solar power by 2030. On the other hand, the African countries are making progress in the exploitation of solar energy, but still, better results can be obtained. Theoretically photovoltaics (PVs) in Africa can produce up to 660,000 TWh [5, 6].
Solar cells and photovoltaics industry are the current promising alternatives for fossil fuels and the rest of non-renewable energy. The nowadays point of research to supply electricity is the enhancement of two factors in the solar cells: the efficiency and cost. Single junction-based PVs have been the dominant and the commonly used structure for many years since the required fabrication process was not heavily cost in addition to the large resultant area for the cells. However, Shockley-Queisser started studying several techniques and structures in order to enhance the efficiency of the solar cell besides tracing down the heat flow and dynamics. Based on his reviews, technologies would never proceed over 31%. The design architecture of multi-junction connected to each other has evolved an outcome that surpasses the limit traced by Shockley-Queisser during his studies on single-junction based devices. The building materials for multi-junctions' structures could be semiconductors materials. The formulation of numerous single p-n junctions together results in multiple p-n junctions. It exhibits stability, better performance including efficiency. Each Incident light source with a specific wavelength would excite carriers in each junction with a net electric current for the whole multijunction cell. The primary aim of invoking the concept of numerous p-n junctions is occurring enhancement in the magnitude of absorbance in the cell. The region of the limited operating wavelength for solar cells needs to be as wide as possible. Since considering high absorbance for the cell active materials and a wide range for the operating wavelength of the incident source, this would reflect in high energy and power conversion efficiency. After different experimental results for multijunction based solar cells, performance has been raised above 43% [8, 9]. The industrial tandem solar cells are commercially used with efficiency reached up to 30% under ordinaiy exposure to sunlight. The effect of focused sunlight sources pushes efficiency by up to 40%
[10]. Note that these results are achieved considering the high cost for manufacturing and many complex modifications.
Modifications are investigated in order to surpass Shockley- Queisser limit. These modifications either in fabrication or structure would maintain high efficiency [11]. The effectiveness of wide- bandgap materials in solar cells will reflect in enhancement for efficiency [12]. Wideband gap-based semiconductors owe an energy bandgap of more than 2.2 eV [12]. Gallium nitride (GaN) and silicon carbide (SiC) are examples of wide bandgap semiconductors of the third generation. The promising characteristics for wide bandgap materials are their highly shifted breakdown point of the electric field. WBG semiconductors are fabricated under high temperature. This is considered an advantage since these materials can resist for a long time under high temperature exposed to the cell [13, 14]. The strategy for WBG usage is decreasing the leakage current in the cell. Since the difference between the lower energy level in the conduction band and higher level in the valence band is higher than 2 eV, this would make the intrinsic carriers' concentration lower than usual. This is the principle for the positive effect caused by WBG materials.
In this chapter, the improvement of the electrical and optical properties of solar cells will depend on the functionalization of a thin natural polymeric layer with adding additives in the form of nanoparticles (i.e. the formation of the nanopolymeric layer) within the active layers in the current solar cell. This can be achieved by incorporating inorganic nanofillers dispersed at the nanoscale within natural polymeric matrices, which produce membranes of polymer nanocomposite (PNC) with enhanced electrical properties. The nanocomposite materials combine the benefits of the polymer matrix ranging from flexibility, polymer processability, and inorganic filler thermal stability [8].
