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| 2. |
- Borgström, Magnus T., et al.
(författare)
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Towards Nanowire Tandem Junction Solar Cells on Silicon
- 2018
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Ingår i: IEEE Journal of Photovoltaics. - 2156-3381. ; 8:3, s. 733-740
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Tidskriftsartikel (refereegranskat)abstract
- The development of photovoltaics as a serious means of producing renewable energy has accelerated greatly in the last ten years, with prices for silicon-based solar cell systems dropping dramatically in the last few years. The next great opportunity for photovoltaics following this competitiveness in prices will be to enhance the cell and panel efficiencies. It is quite generally seen that the most viable platform on which this should be realized will be as augmented silicon solar cells, in which a top cell will be combined with the silicon bottom cell in a tandem configuration, by which the efficiency can be enhanced by a factor from 20% to 50%, depending on details of the approach. In this paper, we report on the status of one such approach, namely, with a top cell comprising III-V nanowires, connected to the bottom silicon cell in a two-terminal or four-terminal configuration. Among the most important opportunities, we show that a substrate-free growth, called Aerotaxy, offers a radical reduction in the total price picture. Besides the description of the key technical approaches, we also discuss the environmental issues.
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| 3. |
- Espinet-Gonzalez, Pilar, et al.
(författare)
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Radiation Tolerant Nanowire Array Solar Cells
- 2019
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 13:11, s. 12860-12869
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Tidskriftsartikel (refereegranskat)abstract
- Space power systems require photovoltaics that are lightweight, efficient, reliable, and capable of operating for years or decades in space environment. Current solar panels use planar multijunction, III-V based solar cells with very high efficiency, but their specific power (power to weight ratio) is limited by the added mass of radiation shielding (e.g., coverglass) required to protect the cells from the high-energy particle radiation that occurs in space. Here, we demonstrate that III-V nanowire-array solar cells have dramatically superior radiation performance relative to planar solar cell designs and show this for multiple cell geometries and materials, including GaAs and InP. Nanowire cells exhibit damage thresholds ranging from ∼10-40 times higher than planar control solar cells when subjected to irradiation by 100-350 keV protons and 1 MeV electrons. Using Monte Carlo simulations, we show that this improvement is due in part to a reduction in the displacement density within the wires arising from their nanoscale dimensions. Radiation tolerance, combined with the efficient optical absorption and the improving performance of nanowire photovoltaics, indicates that nanowire arrays could provide a pathway to realize high-specific-power, substrate-free, III-V space solar cells with substantially reduced shielding requirements. More broadly, the exceptional reduction in radiation damage suggests that nanowire architectures may be useful in improving the radiation tolerance of other electronic and optoelectronic devices.
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| 4. |
- Landquist, Birgit, et al.
(författare)
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Uppdaterad och utökad livscykelanalys av svensk grisproduktion
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Förbättrade produktionsresultat inom svensk grisproduktion, användning av biproduk-ter och djurhälsans betydelse har analyserats i en livscykelanalys. Klimatavtrycket för kött från en svensk medelgris är 2,54 kg koldioxidekvivalenter/kg slaktvikt, vilket är bland de lägsta jämfört med tillgängliga internationella studier. Produktionen av foder står för 54 % av klimatavtrycket och hanteringen av stallgödsel för 36 %. Av foderstaten till den svenska integrerade medelslaktgrisen utgjorde biprodukter 10 % och soja 4 %. Baserat på antalet dagars förlängd uppfödningstid för sjuka grisar, visar vi att 3,4 % av klimatavtrycket beror på ökad foderförbrukning orsakad av fyra utvalda sjukdomar i svenska grisbesättningar. Produktionshöjande åtgärder såsom exempelvis friska grisar och hög fodereffektivitet, övergång till förnybara bränslen inom såväl odling av foder som inom grisuppfödning är viktiga åtgärder för att minska klimatavtrycket givet att det inte påverkar andra miljöaspekter, djurhälsa eller djurvälfärd negativt. En central aspekt är fortsatt utveckling mot välbalanserade foderstater med val av foderråvaror med lågt klimatavtryck, användning av biprodukter och inhemska fodergrödor odlade på ett hållbart sätt.
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| 5. |
- Otnes, Gaute, et al.
(författare)
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Understanding InP Nanowire Array Solar Cell Performance by Nanoprobe-Enabled Single Nanowire Measurements
- 2018
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:5, s. 3038-3046
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Tidskriftsartikel (refereegranskat)abstract
- III-V solar cells in the nanowire geometry might hold significant synthesis-cost and device-design advantages as compared to thin films and have shown impressive performance improvements in recent years. To continue this development there is a need for characterization techniques giving quick and reliable feedback for growth development. Further, characterization techniques which can improve understanding of the link between nanowire growth conditions, subsequent processing, and solar cell performance are desired. Here, we present the use of a nanoprobe system inside a scanning electron microscope to efficiently contact single nanowires and characterize them in terms of key parameters for solar cell performance. Specifically, we study single as-grown InP nanowires and use electron beam induced current characterization to understand the charge carrier collection properties, and dark current-voltage characteristics to understand the diode recombination characteristics. By correlating the single nanowire measurements to performance of fully processed nanowire array solar cells, we identify how the performance limiting parameters are related to growth and/or processing conditions. We use this understanding to achieve a more than 7-fold improvement in efficiency of our InP nanowire solar cells, grown from a different seed particle pattern than previously reported from our group. The best cell shows a certified efficiency of 15.0%; the highest reported value for a bottom-up synthesized InP nanowire solar cell. We believe the presented approach have significant potential to speed-up the development of nanowire solar cells, as well as other nanowire-based electronic/optoelectronic devices.
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| 6. |
- Volpati, Diogo, et al.
(författare)
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Spectroscopic investigations of arrays containing vertically and horizontally aligned silicon nanowires
- 2016
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Ingår i: Materials Research Express. - : IOP Publishing. - 2053-1591. ; 3:12
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Tidskriftsartikel (refereegranskat)abstract
- The properties of nanowire arrays have been investigated mainly in comparison with isolated nanowires or thin films, owing to the difficulty in controlling the nanowire alignment. In this study, we report on arrays containing vertically or horizontally aligned silicon nanowires, whose alignment and structure were determined using x-ray diffraction and scanning electron microscopy. The Raman spectra of the nanowire arrays differ from those of isolated nanowires because of distinct heat dissipation rates of the absorbed energy from the laser, in agreement with recent theoretical calculations. The tailored alignment of the nanowires on solid substrates up to 1 inch of diameter also enabled the observation of resonance modes associated with light trapped into the nanowires. This was proven by comparing the light absorbed and scattered by the arrays, and may be exploited to enhance light harvesting in tandem solar cells. Significantly, the control of the assembly of nanowire arrays may have a direct impact on bottom-up technologies of high anisotropy nanomaterials.
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| 7. |
- Zhang, Yuwei, et al.
(författare)
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Self-Limiting Polymer Exposure for Vertical Processing of Semiconductor Nanowire-Based Flexible Electronics
- 2020
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 3:8, s. 7743-7749
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we demonstrate a vertical processing method to fabricate nanowire (NW)-based devices. This method combines the strong light absorption ability caused by the NW geometry and exposure to dose-dependent clearance properties of a photo-sensitive polymer. By embedding NW arrays in a polymer, the NW light absorption leads to self-limited exposure and selective removal of the polymer. This optical and self-limited exposure pattern definition method can replace more expensive processing equipment, such as reactive ion etching and the use of a mask aligner. Excitingly, this method can be used to enable peel-off of NW arrays from their parent substrate, opening up opportunities to fabricate flexible NW array devices.
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