Toward Fully Solution-Processed Organic Photovoltaics: Spectroscopic Studies on Electronic Structures for Organic Solar Cells with Graphene Electrodes
| Autor: | Jan-Kai Chang, 張然凱 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Heterostructures based on organic semiconductors are fundamentally different and more flexible than those made from conventional covalently bonded inorganics. In particular, organic bulk heterojunction (BHJ) solar cells have been known for their potential as a time-saving, low-cost and lightweight technology. In this work, the electronic properties of internal junctions including donor-acceptor heterojunction, organic/organic and organic/inorganic junctions at each interface within a BHJ solar cell have been studied in detail via photoemission spectroscopy. Promising ways for performance improvement have been developed based on the incorporation of energy ladder, interfacial modification, as well as forming an energetically favorable band alignment by tuning the work function of electrodes. In addition to investigations from the aspect of electronic structure, loss mechanisms induced by interfacial barrier due to band mismatch have been clarified with better understanding of capacitive response provided by impedance spectroscopy. A facile approach that can transfer high-quality graphene along with effective doping was also established based on aqueous intercalation process, enabling n-doped and p-doped graphene for transparent electrode applications. Accordingly, the incorporation of both graphene anode and graphene cathode was successfully carried out to achieve high-performance organic BHJ solar cells with semi-transparency, showing high compatibility with solution-processed organic optoelectronics. Such proposed scheme benefited the integration of graphene with organic BHJ solar cells, which was further developed into a vacuum-free process for device fabrication. Therefore, the development of fully solution-processed semitransparent device distinguishes organic BHJ solar cells as a feasible green energy source for flexible optoelectronics, wearable battery as well as facade integration. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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