| Author: | Wang, Jiajie Ivan |
| Title: | Investigation of solar electric systems based on nano rectenna |
| Degree: | Ph.D. |
| Year: | 2014 |
| Subject: | Photovoltaic power systems. Optical antennas. Nanophotonics. Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Building Services Engineering |
| Pages: | xxiv, 203 leaves : ill. ; 30 cm. |
| Language: | English |
| Abstract: | Renewable energy, as a complement to traditional fuel energy, has received increasing attention. Solar radiation is one particular source of renewable energy that has been widely applied in vehicles, machines, and buildings, among others. There are generally two different ways in which solar energy is used - heat and electricity. Electric power can be obtained from converting solar energy through the use of photo voltaic cells, a conversion process that involves stimulating the electrons on PV cells by solar energy to generate electrical current. Another way of converting solar energy to electrical current is by tapping its electromagnetic wave properties - nano antennas. A nano antenna receives solar/optical energy in a highly efficient way. The energy is then transmitted to the MIM (Metal Insulator Metal) diode for rectification. Finally, the DC current is generated by the diode based on the tunnelling effect.The idea of harvesting solar energy by nano antennas dates back to the end of the 1970's as a type of theoretical research because of fabrication technology. Even to date, most of the research remains within the realm of theoretical study using computer numerical analysis. Only a fewer researchers have managed to fabricate these nano meter scale devices, but how fabrication technology works is worth studying. The aim of this thesis is to study a novel technology for harvesting solar energy by using nano antennas. This technology is developed by using plasmatic properties of the metal for collecting solar energy and tunnelling effect in the MIM diode for optical rectification. A solar-energy-harvesting rectenna system is developed. The rectenna is an antenna with a diode. The whole nano rectenna system consists of a nano antenna, a MIM diode and DC output lines, which are mounted on a silicon substrate. The substrate is chosen as the base board, because of its relative low cost and ease of production, while the nano antennas, made of aluminium, are used to collect solar energy for their relatively high efficiency. The MIM diodes are embedded in the gap of nano antennas in order to reduce the optical loss and to directly receive the optical energy for rectification to DC current. The output DC lines are embedded in the substrate to eliminate interference and to transmit the DC current. Thus the antenna and the MIM diode are integrated into a complete rectenna system. An antenna array is composed of multiple single rectenna units to provide more current output. In this thesis, the method of FDTD (finite-difference time-domain) is employed to study the characteristics of nano antennas, and the tunnelling effect of quantum mechanics is employed to study the characteristics of DC rectification. In summary, this thesis theoretically presents the design and analysis of a rectenna system for harvesting solar energy for electrical application, which is quite different from the traditional photovoltaic technology. It is found that the total conversion efficiency of the rectenna system in an array is 15%. The following contributions have been made in the field of optical nano devices: (1) nano antenna proposed for harvesting solar energy; (2) optical energy rectification; (3) nano device integration; (4) nano antenna array; (5) a complete design procedure for solar-energy-harvesting using nano antennas. |
| Rights: | All rights reserved |
| Access: | open access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b26960898.pdf | For All Users | 5.17 MB | Adobe PDF | View/Open |
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