Abstract
The demands for autonomous energy solutions are increasing rapidly due to the explosive growth in the Internet of Things (IoT) ecosystem. The overall IoT connections have been estimated to reach 35 billion in 2020 and have been projected to reach over 80 billion by the end of 2024. Therefore, sustainable and diverse energy solutions incorporating remote charging are acute to power billions of devices in IoT and other ubiquitous electronics. Due to ease of implementation and availability, energy scavenging by harvesting power from radio frequency (RF) sources is a promising energy solution. A typical RF harvester comprises two functional units: an antenna to gather RF energy and a rectifier circuit to convert them to electric energy such as voltages to power up electronic devices. RF rectifying diodes, as the simplest rectifying components, are vital for such energy autonomy systems.
Emerging printing and coating techniques, with their low-cost and ease of fabrication, make solution-processed and printed electronics very attractive. It enables researchers to explore new ways of material processing to develop devices, circuits, and systems, which are difficult to achieve with traditional wafer-based manufacturing techniques. With the steady development in printing and coating methods, it is of great interest to develop solution-processed and printed, low-cost RF energy harvesters with unconventional semiconductor materials, such as organic polymers and metal oxides. Due to unique bonding and carrier transport mechanism, solution-processed organic and metal oxide diodes have dramatically different properties compared to their Si-based counterparts; their circuits have unique characteristics, and their optimization can differ strongly from conventional inorganic equivalents. Therefore, as one of the most fundamental active electronic components, solution-processed rectifying diodes are not only essential to low-cost RF energy harvesters but also an important steppingstone to understanding other solution-processed electronic devices.
The work presented in this thesis, including the publications therein, focuses on the development and analysis of solution-processed thin film organic and metal oxide diodes and their rectifier circuits for RF energy harvesting applications. The thesis discusses how to improve the properties of the diodes, especially their frequency response. The gravure printed organic diodes offer improved electrical performance at 13.56 MHz whereas the solution-processed spin-coated indium oxide diodes operate up to and above 0.7 GHz. Furthermore, the thesis demonstrates fully printable RF energy harvesters based on printed diodes with working distance from a few cm to 4 meters at 13.56 MHz. The utilization in an autonomous energy harvesting and storage unit is presented as well. The unique properties of the printed diodes are investigated when integrated into harvester circuits. The results in this thesis demonstrate the capability of solution processed rectifying organic and metal oxide diodes utilized in RF energy harvesting systems for IoT applications.
Emerging printing and coating techniques, with their low-cost and ease of fabrication, make solution-processed and printed electronics very attractive. It enables researchers to explore new ways of material processing to develop devices, circuits, and systems, which are difficult to achieve with traditional wafer-based manufacturing techniques. With the steady development in printing and coating methods, it is of great interest to develop solution-processed and printed, low-cost RF energy harvesters with unconventional semiconductor materials, such as organic polymers and metal oxides. Due to unique bonding and carrier transport mechanism, solution-processed organic and metal oxide diodes have dramatically different properties compared to their Si-based counterparts; their circuits have unique characteristics, and their optimization can differ strongly from conventional inorganic equivalents. Therefore, as one of the most fundamental active electronic components, solution-processed rectifying diodes are not only essential to low-cost RF energy harvesters but also an important steppingstone to understanding other solution-processed electronic devices.
The work presented in this thesis, including the publications therein, focuses on the development and analysis of solution-processed thin film organic and metal oxide diodes and their rectifier circuits for RF energy harvesting applications. The thesis discusses how to improve the properties of the diodes, especially their frequency response. The gravure printed organic diodes offer improved electrical performance at 13.56 MHz whereas the solution-processed spin-coated indium oxide diodes operate up to and above 0.7 GHz. Furthermore, the thesis demonstrates fully printable RF energy harvesters based on printed diodes with working distance from a few cm to 4 meters at 13.56 MHz. The utilization in an autonomous energy harvesting and storage unit is presented as well. The unique properties of the printed diodes are investigated when integrated into harvester circuits. The results in this thesis demonstrate the capability of solution processed rectifying organic and metal oxide diodes utilized in RF energy harvesting systems for IoT applications.
| Original language | English |
|---|---|
| Place of Publication | Tampere |
| ISBN (Electronic) | 978-952-03-2344-8 |
| Publication status | Published - 2022 |
| Publication type | G5 Doctoral dissertation (articles) |
Publication series
| Name | Tampere University Dissertations - Tampereen yliopiston väitöskirjat |
|---|---|
| Volume | 575 |
| ISSN (Print) | 2489-9860 |
| ISSN (Electronic) | 2490-0028 |