| dc.description.abstract | The increase in energy use, and the subsequent emission of greenhouse gases from fossil fuel usage has led Earth to the global climate crisis we are facing today. The goal of the Paris agreement is to limit global warming to below 2 °C, and in order to achieve this, emissions must be cut. A key to cutting emissions is to switch the energy sources to renewable ones, which emit no or very low levels of CO2 relative to fossil fuels. One of the most promising renewable energy converters are photovoltaic solar cells. Solar cells have reached good conversion efficiencies, but still has a potential for improvement. In this thesis, the objective is to investigate if further increase in thin-film solar cell technology can be obtained using plasmonic nanostructures. The work has been carried out using a Finite-Difference Time-Domain (FDTD) simulation tool for electromagnetics. It has been determined that the light in-coupling of a CdTe and GaAs thin-film solar cell with ITO may be enhanced by adding plasmonic nanoparticles of aluminum to the front surface of the cells. The GaAs cell obtains an absorption enhancement of 0.75 %, while the CdTe cell when simulated without a glass substrate gains an absorption enhancement of 1.76%. It was found that the use of indium as a plasmonic scattering mechanism was only effective for the CdTe cell without glass substrate, where it resulted in an absorption enhancement of 0.59 %. Furthermore, it was found that the addition of the plasmonic nanoparticles to the front surface of a CdTe cell with the glass substrate gave no enhancement. As a part of the ongoing work in the research group where this work was carried out, a part of this thesis was dedicated to test depositions of Al nanoparticles onto silicon solar cells. Al nanoparticles were synthesized by some collaborators at Rice University in the US, and deposited on silicon substrates and silicon solar cells using various deposition methods. The solar cell efficiency was compared to its pre-deposition state, and unfortunately these results did not show the positive response expected. Several potential reasons for this are suggested, such as large amount of agglomerated nanoparticles in the solution, and increased series resistances due to Al nanoparticles coated on the back of the cell. However, this needs to be investigated further before any conclusive statement can be made | |
