Solar Energy Harnessing - Dissertation Example

?Background: The world’s most common source of energy, the fossil fuels, is fast getting used up. The problem with fossil fuels is that they aren’t renewable; once consumed, you have to dig up more, and consume that as well. Right now, we have reached a point where we are fast ridding our world of its fossil fuel resources. Thus, the advances in science and technology are now focusing research and development projects in the field of renewable energy. Renewable energy sources are arguably the future of human survival in this world. One of the very important paradigms of research in the field of renewable energy sources is solar energy. Solar energy, if harnessed to its fullest, can provide the whole world with more than enough energy for a year, in just a single day. Science and technology is still far from that point. Solar energy harnessing with today’s inventions is still expensive and inefficient, making this a very exploitable research field, with the promise of a better world. Solar energy will soon come out as a multibillion dollar industry, and only those nations will prosper through it, which spend time, efforts and money in this field today. Solar energy harnessing through photovoltaic cells is a very promising field. To enhance the efficiency, increasingly thin films are being prepared. PVs are made out of doped semiconducting materials, which have relatively high resistivity as compared to common good conductors. Thus, photovoltaic cells are coated with conducting materials on their surface. These are thin films themselves, whose sole purpose is to behave as a conducting medium. The coatings are done over the photovoltaic layers, such that they are present between the light source and the photovoltaic layer. This means that the coatings have to be highly transparent for light transmission as well. The materials employed for this purpose are termed as Transparent Conducting Oxides, which are nothing but doped oxides that have very high conductivity and transmission. TCOs may have a variety of functions, such as transparent electrical contacts, antireflection coatings and chemical barriers, in photovoltaic films (Perkins et. al. 20051). It is to be noted that the energy band gap theory suggests that transparency of a material is closely related to the electrical behavior of a material, more specifically its resistivity. Transparency of a material is higher if the band gap between the valence and conduction band is high. If the band gap is high, the resistivity is high too. Thus it is difficult to have both high transparency and low resistivity together. To achieve this, doping is done in selected semiconductors, which can modify their properties to give us transparent layers with high conduction (Nave, 20102). A lot of research has been done in this field for over 50 years now and every project has led to the opening of a new chapter rather than closing out different chapters in the research. This is suggestive of the prospects of research in this field. The most important property of TCOs is their conductivity, and a lot of research has been done on that (Minami, 20003; Lewis and Paine, 20004) on aluminum doped zinc oxide, tin doped indium oxide, lead oxides, cadmium oxides, and their combinational oxides. These researches have indicated that there exists potential for engineered transparent conducting oxides to be formed with tailored properties (Freeman et. al. 20015). Transparency and light trapping has also been studied in detail in these papers. The main emphasis of the researches is to study composition-property behaviors. Some endeavors have also been made for synthesis and characterization of these thin films (Banarjee et. al. 20036; Coutts and Young, 20007; Gurumurugan et. al. 19948; Freeman et. al. 2001). Researchers have also used surface characterization techniques to study how electrical, chemical and transparency properties of TCOs depend on the surface layer. The electronic/defect structure of the surface layers has a huge impact on the electrical properties of the layer by increasing conductivity with high defects, though it has a negative impact on the transparency and light trapping ability of the film. The previous discussion points to the high prospects of research as well as the need for evolutionary research in this field at the industry. Academic Impact: For a research to be fruitful to other researchers, it should always be done on a subject that has yet to be explored. My aim as a researcher in the field of TCOs will be to read papers from online journals that are up to date on research progress. This will help me understand what research horizons can be embarked upon and what researching in that field will benefit the rest of the scientific community. The report I shall produce will not be a review report on other papers that I go through. My aim will be to learn what has been done yet, and take it one step further. Fortunately or unfortunately, TCOs have a lot of research prospect because there is tons of work to do in that field. The combinational science of oxides, which can lead to tailoring of properties according to requirements, suggests that the more research is done in this field, the lesser. My own focus will be to study surface features and surface structural morphology including defects’ characterization, which is a very healthy and important field of research. I will aim to not only produce results for light trapping properties and transparency of specific structures, but also generalize them and predict characterization models based on empirical results that I may produce from my research. To make sure that the scientific community benefits from it, I will attempt to utilize the time and money effectively. Not every research project produces the results hoped for, which makes researchers forgo what they are doing. That is a wrong approach as the seemingly awry results may be valuable in other ways. Thus, my efforts will be to report whatever results I gather from the research, to the scientific community, for the benefit of my country as well as the world at large. Research Hypothesis and Objectives: The light trapping properties of Transparent Conducting Oxides depend highly on the surface structure and morphology. A correlation between the two can be developed on the basis of spectroscopic and optical angular analysis, by analyzing many different surface structures. Thus, the analysis can result in developing methods to increase PV cells’ efficiency. TCO transparency and electrical conductivity have some inherent limitations, which have to be considered in the light of the band gap theory (Chen et. al. 20009). Modifications in the surface structure can result in a high increase in the efficiency of the photovoltaic cell through increased light trapping. This is a relatively unexplored field, as most research has been done on the transparency and conduction properties of these films. Relatively does not suggest that no research has been done, yet there is a lot to be done in this field. A general characterization technique developed for this analysis as well as finding of empirical relations for increasing light trapping of TCOs through surface modifications will help the scientific community further the research in this field, as well as helping industries produce TCO coated PVs with high efficiency. My research shall focus on first obtaining spectral images of the films, to observe their surface characteristics. Tests will then be done on the light trapping ability of the films, by measuring their efficiency based on the optical angular analysis technique. After the tests are conducted, the focus will shift to developing relations between the two and conducting further tests by making a few surface modifications, characterizing the modifications and then measuring their efficiency. These will first be done on a certain type of material, and the lessons learnt will be used to apply the same procedure to different TCO materials. Programme and Methodology: Following the research methodology described above, some milestones can be ascertained to measure the progress of the program: 1. Literature survey. 1 week 2. Drafting literature survey for research guideline. 2 days 3. Agreeing upon research theme with supervisor. 1 day 4. Procurement of research equipment. 2 days 5. Procurement or synthesis of multiple TCO films. 2 days 6. Spectroscopic characterization of TCO films, to study morphological factors that may influence light trapping. 1 week 7. Carrying out optical angular analysis of films to measure light trapping. 1 week 8. Studying multiple films with different morphological factors and develop relations between light trapping and surface structure. 1 week 9. Modifying surface features to test empirical relations. 1 week 10. Inferring conclusions, comparing results with surveyed literature and writing dissertation on the said topic. 6 weeks Kindly let me have some information about your team so I can add information on team management. Read More