Thin-film crystalline solar cells for low capex manufacturing
Abstract/Contents
- Abstract
- High capital expenditure (CapEx) in manufacturing has become a major barrier to the sustainable growth of the photovoltaic (PV) solar cell industry. Therefore, it is crucial to develop new technologies that could enable low capex manufacturing in the PV industry. Among these, ultra-thin crystalline solar cell technology, with active semiconductor layers 10--100 times thinner than conventional solar cells, is a promising one, as it could both reduce both material consumption reduce capex and quite surprisingly, and enhance the energy conversion efficiency. In order to achieve high efficiency, it is important to reduce recombination with better passivation technology to increase voltage and improve light absorption through photon management to increase the current. The first half of this dissertation focuses on contact passivation using carrier selective layers. Although ultra-thin crystalline silicon (c-Si) solar cells could suppress bulk recombination and enhance Voc through better carrier confinement, the contact recombination at the unpassivated metal-semiconductor interface of the metal Ohmic contacts significantly reduces the Voc. An electron-selective TiOx layer is introduced for the n-contact, while a hole-selective NiOx layer is introduced for the p-contact. The carrier-selective effects of the two materials are evaluated through the design, fabrication and characterization of contact resistivity, which reveal the conducting effect for majority carriers and blocking effect for minority carriers. Also, contact recombination factor J0c is characterized for both layers, which demonstrate the contact passivation effect. In addition, the effect of rapid-thermal-annealing (RTA) is also evaluated under different temperature conditions. Finally, the NiOx layer is successfully integrated with a 2-μm thin-film c-Si solar cell, and the Voc is improved by 2-7 mV. The second part of this dissertation discusses the optical engineering and absorption enhancement in nanostructured solar cells. First, for the c-Si solar cells, the SiNx nanostructured dielectric layer is introduced as a new approach to design and fabricate whole-wafer nanostructures. The SiNx nanostructured dielectric layer is applied onto a 2.9-μm ultra-thin c-Si solar cell. The short-circuit-current (Jsc) of the cell is improved by 32% and the energy conversion efficiency is enhanced by 44%. Also, the SiNx nanostructured dielectric layer is integrated onto a commercial 40-μm ultra-thin c-Si layer, and its reflection loss is suppressed to below 5% over a wide spectral and angular range. Second, for crystalline III-V solar cells, the design and optimization of nanostructured window solar cells are described through a set of carefully designed experiments. In addition, a graded window layer design is demonstrated, which shows the importance of reducing the parasitic absorption and minority carrier loss inside the nanostructured window.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Chen, Yusi |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering. |
| Primary advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Cui, Yi |
| Thesis advisor | Fan, Shanhui, 1972- |
| Advisor | Cui, Yi |
| Advisor | Fan, Shanhui, 1972- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Yusi Chen. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Yusi Chen
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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