Tuning the shape of semiconductor nanowires for advanced photovoltaics
Abstract/Contents
- Abstract
- Tuning the shape of nanostructures can have a strong effect on photon management and charge carrier collection for photovoltaics. Here two examples of nanowire shape designing are demonstrated: nanocones and branched nanowires. Photon management, involving both absorption enhancement and reflection reduction, is critical to all photovoltaic devices. It can improve the efficiency by minimizing optical and electrical losses, and cut cost by reducing material usage, process time and capital investment. Here I demonstrate a novel solar cell structure with an efficient photon management design. The centerpiece of the design is a novel nanocone structure, which is fabricated by a scalable low temperature process. With this design, devices with very thin active layer can achieve near perfect absorption because of both efficient antireflection and absorption enhancement over a broad spectral range and a wide range of angles of incidence. More strikingly, the design and process is not in principle limited to any specific material system, hence it opens up exciting opportunities for all classes of photovoltaic devices. I have used amorphous silicon and dye sensitized solar cells as two examples to demonstrate the concept. The device efficiencies of this design are significantly better compared to conventional devices. Moreover, I also have explored absorption enhancement on a sub-wavelength scale, compared to "classical" light trapping limits. PbSe nanocrystals have shown a greatly enhanced multi exciton generation (MEG) effect, one important step toward third generation solar cells. However, it is difficult to extract generated carriers from nanocrystals without good transport pathways. Three dimensional branched nanowire or nanotube networks, with strong quantum confinement within two dimensions, and the connected third dimension as an efficient charge carrier pathway, could be ideal for enhancing the MEG effect, light absorption, and carrier collection. I successfully demonstrate a large area growth of PbSe hyperbranced and chiral branched nanowires on a variety of substrates. More excitingly, Chiral branched nanowires reveal a new nanowire growth mechanism, dislocation driven growth, which can be applied to a variety of materials.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Zhu, Jia |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering |
| Primary advisor | Cui, Yi, 1976- |
| Thesis advisor | Cui, Yi, 1976- |
| Thesis advisor | Howe, Roger Thomas |
| Thesis advisor | McGehee, Michael |
| Advisor | Howe, Roger Thomas |
| Advisor | McGehee, Michael |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Jia Zhu. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2010. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2010 by Jia Zhu
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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