dc.identifier.uri |
http://dx.doi.org/10.15488/16952 |
|
dc.identifier.uri |
https://www.repo.uni-hannover.de/handle/123456789/17079 |
|
dc.contributor.author |
Winter, Michael
|
eng |
dc.date.accessioned |
2024-04-12T05:37:40Z |
|
dc.date.available |
2024-04-12T05:37:40Z |
|
dc.date.issued |
2024 |
|
dc.identifier.citation |
Winter, Michael: Carrier lifetime instabilities in the bulk and at the surfaces of crystalline silicon solar cells triggered by fast-firing processes. Hannover : Gottfried Wilhelm Leibniz Univ., Diss., 2024, vi, 115, XIV S., DOI: https://doi.org/10.15488/16952 |
eng |
dc.description.abstract |
Carrier lifetime instabilities in crystalline silicon solar cells under illumination affect
the long-term stability of photovoltaic modules in view of the steadily increasing
conversion efficiency of the solar cells used in state-of-the-art modules. This thesis
examines carrier lifetime degradation and regeneration – both in the bulk and at
the surfaces of different crystalline silicon materials and solar cells made thereof –
after a fast-firing step has been applied in a conveyor belt furnace. It is shown
that fast-firing triggers degradation effects under illumination. However, fast-firing
is also a key step in the contact formation of screen-printed contacts, which is the
dominating metalization technique applied today in the solar cell production.
Independent of fast-firing in a standard conveyor belt furnace, the bulk carrier
lifetime of boron-doped Czochralski-grown silicon (Cz-Si:B) is dominated by the
light-induced activation of a boron-oxygen (BO) defect. Gallium-doped Czochralski-grown silicon (Cz-Si:Ga) and boron-doped float-zone silicon (FZ-Si:B) – both not
prone to BO-related degradation –, however, show a strongly temperature-dependent degradation of the bulk lifetime activated under simultaneous illumination. The equilibrium state establishing between activated (recombination-active) and deactivated (recombination-inactive) state of the defect is dependent on the temperature and the activation and deactivation of the defect are reversible processes. It is shown that the in-diffusion of hydrogen from hydrogen-rich silicon nitride layers (SiNy:H), used for the surface passivation and as antireflection coating, into the silicon bulk during fast firing plays a key role for the so-called ”light- and elevated-temperature-induced degradation”(LeTID) in all three materials – namely Cz-Si:B, Cz-Si:Ga, and FZ-Si:B. Experiments on the very defect-lean FZ-Si:B material furthermore suggest a second participant in the defect reaction of LeTID besides hydrogen.
LeTID is also observed on ”polycrystalline silicon on oxide” (POLO) backjunction
(BJ) solar cells fabricated on Cz-Si:Ga. The maximum relative degradation extent
of the conversion efficiency η of only 2%rel at 140 °C and 1 sun, however, shows that POLO BJ cells are remarkably stable regarding light-induced degradation. Through prolonged illumination at elevated temperatures a partial permanent deactivation of the LeTID defect is possible.
In addition to bulk degradation, thermally-induced instabilities of the phosphorus-doped POLO passivation layers after fast-firing are discovered. The degradation
and the following regeneration of the surface passivation quality – described by the
saturation current density J0 – is correlated with high probability with the hydrogen
passivation of interface states. |
eng |
dc.language.iso |
eng |
eng |
dc.publisher |
Hannover : Institutionelles Repositorium der Leibniz Universität Hannover |
|
dc.rights |
CC BY 3.0 DE |
eng |
dc.rights.uri |
http://creativecommons.org/licenses/by/3.0/de/ |
eng |
dc.subject |
solar cell |
eng |
dc.subject |
silicon |
eng |
dc.subject |
degradation |
eng |
dc.subject |
carrier lifetime |
eng |
dc.subject |
Solarzelle |
ger |
dc.subject |
Silizium |
ger |
dc.subject |
Degradation |
ger |
dc.subject |
Ladungsträgerlebensdauer |
ger |
dc.subject.ddc |
530 | Physik
|
eng |
dc.title |
Carrier lifetime instabilities in the bulk and at the surfaces of crystalline silicon solar cells triggered by fast-firing processes |
eng |
dc.type |
DoctoralThesis |
eng |
dc.type |
Text |
eng |
dcterms.extent |
vii, 115, XIV S. |
eng |
dc.description.version |
publishedVersion |
eng |
tib.accessRights |
frei zug�nglich |
eng |