dc.contributor.author | Martinsen, Fredrik Aleksander | |
dc.date.accessioned | 2015-11-10T13:17:45Z | |
dc.date.available | 2015-11-10T13:17:45Z | |
dc.date.issued | 2015 | |
dc.identifier.isbn | 978-82-326-1127-0 | |
dc.identifier.issn | 1503-8181 | |
dc.identifier.uri | http://hdl.handle.net/11250/2359997 | |
dc.description.abstract | In this work it has been shown that microwire radial junction solar cells
can be realized from silicon core glass fibers made via the molten core
fiber drawing method starting with low quality silicon. Through a segregation
based purification method the original 3N purity starting material
turned into 5N purity silicon micro-fibers that were found to solidify
with millimetre-sized grains. The segregation process itself has
been investigated through solidification studies on silicon micro-flakes
and the purification process has been found to be in agreement with
non-equilibrium segregation models. The silicon fibers have been characterized
with a wide range of techniques, including Hall measurements,
electron microscopy and electron beam induced current. The latter technique
showed a ≈ 40 µm bulk minority carrier diffusion length in the
fibers, and together with adequate doping densities and surface quality
the fibers were determined to be of sufficient quality for use as solar
cells. Working prototype solar cells were produced both with a vertical
geometry as well as with a horizontal geometry and showed in both cases
efficiencies of approximately 3.5%. The limitation of efficiency for both
geometries is believed to be non-optimized processing, with the quality
of the material itself suggesting that much higher efficiencies are possible.
In both solar cell geometries avenues for achieving high light absorption
per unit of silicon were addressed and evidence that up to ≈ 90 % of the
incident sunlight can be absorbed by employing only ≈ 10 % as much
silicon as for a wafer based cell. Due to dimensions and flexibility of
the fibers, they offer the possibility of realizing flexible and/or partially
transparent crystalline silicon solar cells. | nb_NO |
dc.language.iso | eng | nb_NO |
dc.publisher | NTNU | nb_NO |
dc.relation.ispartofseries | Doctoral thesis at NTNU;2015:235 | |
dc.title | Silicon microwires as solar cells | nb_NO |
dc.type | Doctoral thesis | nb_NO |
dc.subject.nsi | VDP::Mathematics and natural science: 400::Physics: 430 | nb_NO |