In the first wave of commercialization of organic electronics, about ten years ago, active-matrix organic light-emitting diode (AMOLED) displays became the first large-scale industrial application of organic electronic devices. The victory continues and AMOLED displays attain an ever-increasing market share in the global display industry. In the second wave, organic solar cells are about to enter the mass-production stage, and the possibility for low-cost production on flexible substrates will revolutionize the solar in-dustry. The third wave will be the implementation of organic thin-film transistors for truly flexible, printed, large-area circuits. However, there is a multitude of challenges with regard to device physics, material, and process engineering which need to be overcome to make organic thin-film transistors fit for the step into industrial fabrication.
The focus of this thesis is at organic thin-film transistors, covering the whole spectrum
of device physics, design principles, and the exploration of new applications. In particular, charge carrier transport and injection in vertical organic transistors with ultra-short channel length are investigated in order to derive device architectures suitable for high and ultra-high frequency operation. Self-heating and a strongly thermally activated charge carrier transport at high current densities are identified as the limiting factors for high-frequency operation on low thermal conductivity, flexible substrates. Besides fundamental questions on charge carrier transport, this thesis also addresses questions related to the device fabrication. In particular, new fabrication methods for vertical organic transistors are proposed enabling reliable and stable device operation and integration of ultra-short channel length devices without using costly high-resolution patterning techniques.
Beyond conventional organic thin-film transistors, this thesis explores possible paths for the fourth wave of organic electronics. In this context, mixed ionic-electronic conductors and organic electro-chemical transistors (OECTs) are identified as highly promising approaches for electronic bio-interfaces enabling ultra-sensitive detection of biological signals. Furthermore, these systems show fundamental properties of biological synapses, namely the synaptic plasticity, which renders the possibility to build brain-inspired, neuromorphic networks enabling highly efficient computing. In particular, the combination of OECTs acting as sensor units and self-learning neural networks at once enables the development of intelligent tags for medical applications.
Overall, this thesis adds substantially new insight into the field of organic electronics and draws a vision towards further research and applications. The advancements in the field of vertical organic transistors open new perspectives for the implementation of organic transistors in high-resolution AMOLED displays or radio-frequency identification tags. Furthermore, the exploration of OECTs for neuromorphic computing will create a whole new research field across the disciplines of physics, material, and computer science.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:76379 |
| Date | 27 October 2021 |
| Creators | Kleemann, Hans |
| Contributors | Leo, Karl, Helm, Manfred, Zaumseil, Jana, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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