Public defence in Advanced Materials and Photonics, M.Sc.(Tech.) Lassi Hällström
Public defence from the Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering
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The title of the thesis: Computer simulations for designing green energy solutions
Doctoral student: Lassi Hällström
Opponent: Prof. Martijn Zwijnenburg, University College London, UK
Custos: Prof. Ilkka Tittonen, Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering
The research presented in the thesis covers two separate cases of developing computer models explaining the operation of renewable energy devices. The first case is electricity production from streaming current in nanoscale porous structures, driven by constant evaporation of water. The porous structure presents a multiphase fluid dynamics problem, where the flow of water generating the electricity depends on various material properties and ambient conditions. The work in this thesis demonstrates how a carefully designed multiphysics simulation can not only reproduce experimental results known when building the model, but also produce emergent behaviour that can be experimentally verified.
The second focus of the research is photoelectrochemical hydrogen production, converting sunlight to hydrogen with a single, monolithic semiconductor device without the need for electrical grid connections. This case is first simulated using a semi-classical theory based on the Boltzmann transport equation. However, as the design of new materials and electrode geometry increasingly utilizes nanoscale features, the classical approximations behind the Boltzmann equation are no longer accurate. Another method to simulate the semiconductor electrodes is the quantum mechanical formalism of nonequilibrium Green's functions (NEGF), which has been widely utilized in simulating solar cells and transistors. This work demonstrates that NEGF can be applied to modeling photoelectrochemical devices, offering significant improvement over classical models.
In general, the research results presented in the dissertation show how computational models can help not only understanding the behaviour of nanoscale solutions for renewable energy, but also provide critical ability to optimize device design to maximize the efficiency. The computer models created as a result of the research can be applied to the practical design of future energy production methods and offer new insight to the basic principles of the photoelectrochemical phenomenon and porous materials.
Thesis available for public display 10 days prior to the defence at: https://aaltodoc.aalto.fi/doc_public/eonly/riiputus/
Contact information:
| lassi.hallstrom@aalto.fi |
See also:
Doctoral theses in the School of Electrical Engineering: https://aaltodoc.aalto.fi/handle/123456789/53
Zoom Quick Guide: https://www.aalto.fi/en/services/zoom-quick-guide