Surface Characterization of Textured Al Foil for Thin Film Flexible Solar Cells

Surface Characterization of Textured Al Foil for Thin Film Flexible Solar Cells

Rath, Chinmaya (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Photovoltaic Materials and Devices)

Smets, A.H.M. (mentor)
Limodio, G. (graduation committee)

Delft University of Technology

Electrical Engineering | Sustainable Energy Technology

Flamingo PV

2022-03-07

With an increase in population, there is increasing pressure and higher demand in world energy production. Even though there is a high dependency on fossil fuels renewable energy usage has seen a sharp rise in recent years. Solar energy is a major player and contributes a lot to this field. The thin-film solar cell which is a part of second-generation photovoltaic technology is faster and easier to manufacture. What makes them even more desirable is that they are lightweight, cost-effective, and can be manufactured by roll-to-roll production. The transparent conductive oxide layer acts as a front contact for a solar cell and thus plays a major role in guiding the incident light towards the active layer. This TCO has to be deposited on the aluminium foil to utilize its high conductivity and transparency in the active wavelength.
This thesis is part of the FLAMINGO PV (Flexible Lightweight Advanced Materials in Next Generation of Photovoltaics) project with collaboration between HyET Solar B.V and TU Delft. Aluminium foil is used by HyET solar as a substrate for TCO deposition. The bare aluminium foil has high roughness values and imperfections due to the presence of milling tracks and pinholes. The objective of the thesis is to do structural and optoelectrical characterization on this substrate foil and TCO using different process methods.
Bare aluminium foil received by HyET solar which was pre-treated showed a higher roughness value when compared with the untreated samples. This also provided good correlation data with one of the supplier companies. Morphological analysis showed 2020 factory baseline samples having more milling tracks and pinholes compared to 2021 factory baseline samples. The pre-treated sample showed the presence of precipitants which was not the case in untreated samples. FLAM02 textured aluminium foils showed higher roughness values when compared to the 2020 and 2021 factory baseline but this has an overall better impact on its optical property. For Al + TCO samples structural characterization showed the presence of milling tracks and pinholes. Using a scanning electron microscope the optical thickness of TCO was confirmed. For TCO + Carrier foil fewer milling tracks were noticed while characterizing them with SEM and 3D confocal microscope.
Optical characterization for the textured sample shows a similar value in diffused reflectance between the 2020 and 2021 factory baseline and a small increase in specular reflectance for 2020 factory baseline samples. FLAM02 textured samples showed a higher value in diffused reflectance and haze as compared to factory baseline 2021 and FLAM01 textured samples. Electrical characterization done on TCO + Carrier foil where a low free carrier concentration and high mobility is desired.

Solar Energy
Thin Film Solar Cells
Surface Characterization
TCO

http://resolver.tudelft.nl/uuid:c26c5798-908f-41ce-b935-f5e7a8ecab05

2024-03-07

51.9989054068997, 4.373494153775861

Student theses

master thesis

© 2022 Chinmaya Rath