New Developments in Solar Energy Conversion: From Fundamental Two-Dimensional Materials to Advanced Concentrating Photovoltaic Modules
[Thesis]
Islam, Kazi M.
Escarra, Matthew D.
Tulane University School of Science and Engineering
2020
173 p.
Ph.D.
Tulane University School of Science and Engineering
2020
The importance of renewable energy technologies is more critical than ever now in 2020. Among the different types of renewable energy sources, solar energy is especially promising because of its abundance. This Ph.D. dissertation focuses on harnessing solar energy on two different scales. At the atomic scale, nanometer-thick two-dimensional (2D) transition metal dichalcogenides (TMDCs) are used for making ultra-thin photovoltaic (PV) cells along with other optoelectronic devices such as transistors and photodetectors. The optical properties of these nanomaterials are investigated via spectroscopic ellipsometry, showing birefringence and other new features. Schottky-junction photovoltaic devices are designed, fabricated, and characterized with 2D MoS2 and carrier-selective asymmetric contacts such as Ti and Pt for electron and hole collection, respectively. 2D TMDCs have direct bandgaps compared to their bulk counterparts, enabling strong light-matter interactions in these materials. Because of their atomically-thin nature and excellent optoelectronic properties, these materials are good candidates for solar cells with record-high specific power density, i.e., power/mass (W/kg) and power/volume (W/m3). Going from the nanoscale to the micron- and centimeter-scale, transmissive microfluidic channels are developed for actively cooling concentrating photovoltaics (CPV) in a hybrid energy conversion system. The hybrid solar receiver consists of an optically transmissive CPV module on the front and a thermal receiver at the back, coupled together by the transmissive microfluidic CPV active cooling. While the CPV module absorbs the high energy photons and converts them directly into electricity, the thermal receiver receives the low energy photons and converts them into high-temperature process heat. The transmissive cooling channels ensure that the unabsorbed photons in the CPV module can make their way to the thermal receiver while preventing the solar cells from overheating. On top of that, the heat energy absorbed by the cooling water in the microchannels can be extracted and used as low-temperature process heat, thus providing a third energy stream. With these two unique approaches, this dissertation aims to contribute to the ever-expanding field of solar energy conversion and point towards a greener future.
Alternative energy
Applied physics
Materials science
Nanotechnology
Optics
Physics
Islam, Kazi M.
Escarra, Matthew D.
Tulane University School of Science and Engineering