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Nitsche Kvalvik, Julie; Hansen, Per-Anders Stensby & Nilsen, Ola
(2019).
Area-selective deposition of MoO3 thin films by atomic layer deposition.
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Hansen, Per-Anders Stensby
(2018).
Shining a new light on solar energy harvesting.
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Hansen, Per-Anders Stensby
(2018).
Shining a new light on solar energy harvesting.
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Hansen, Per-Anders Stensby
(2018).
Shining a new light on solar energy harvesting.
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Hansen, Per-Anders Stensby
(2018).
Shining a new light on solar energy harvesting.
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Hansen, Per-Anders Stensby
(2018).
Shining a new light on solar energy harvesting.
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Hansen, Per-Anders Stensby; Zikmund, Tomas; Yu, Ting; Nitsche Kvalvik, Julie; Aarholt, Thomas & Prytz, Øystein
[Show all 8 contributors for this article]
(2018).
Aromatic-fluoride nanocomposite materials by atomic layer deposition.
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Hansen, Per-Anders Stensby; Meijerink, Andries & Nilsen, Ola
(2018).
Strong TiO2 sensitization of Tb3+ by preventing Ti-Tb charge transfer quenching in subnanometer multilayer structures.
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Hansen, Per-Anders Stensby; Nesteng, Hanne; Svendsen, Ole Joachim & Nilsen, Ola
(2018).
Blue, green and red emitting lanthanide-organic hybrid films excitable with long wavelength UV.
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Getz, Michael; Hansen, Per-Anders; Nilsen, Ola & Fjellvåg, Helmer
(2015).
Down Conversion in YbVO4
and YVO4:Yb3+ Thin Films
Synthesized by Atomic Layer Deposition
.
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Getz, Michael; Hansen, Per-Anders; Nilsen, Ola & Fjellvåg, Helmer
(2015).
Down Conversion in YbVO4 and YVO4:Yb3+ Thin Films
Synthesized by Atomic Layer Deposition
.
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Getz, Michael; Hansen, Per-Anders; Fjellvåg, Helmer & Nilsen, Ola
(2014).
Enhancing the Efficiency of Solar Cells Using Luminescent EuxTiyPzOw Thin Films Synthesized by ALD.
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Getz, Michael; Hansen, Per-Anders; Nilsen, Ola & Fjellvåg, Helmer
(2014).
Properties of Luminescent Europium Titanium Phosphate Thin Films Synthesized by ALD.
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Getz, Michael; Hansen, Per-Anders; Fjellvåg, Helmer & Nilsen, Ola
(2013).
Avoiding Concentration Quenching of Luminescencewith Thin Films Grown by ALD.
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Hansen, Per-Anders; Fjellvåg, Helmer; Nilsen, Ola & Finstad, Terje
(2011).
Atomic layer deposition of lanthanide oxides.
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Hansen, Per-Anders
(2010).
Energyconversion materials for PV applications.
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Hansen, Per-Anders
(2010).
Energyconversion materials for PV applications.
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Both, Kevin Gregor; Chatzitakis, Athanasios; Bergum, Kristin; Hansen, Per-Anders Stensby; Prytz, Øystein & Norby, Truls
(2023).
Plasmonically Enhanced Photocatalysis: Synthesis, Physical Properties, and Applications.
University of Oslo Livrary.
ISSN 1501-7710.
Full text in Research Archive
Show summary
In this work, plasmonic metal nanoparticles (MNPs) are utilized to improve the photoelectrochemical (PEC) response of strontium titanate (STO). These MNPs were introduced by either direct exsolution, i.e., nickel (Ni), copper (Cu), iron (Fe), ruthenium (Ru), and silver (Ag), or by galvanically replacing exsolved less noble MNPs, i.e., Ni by Gold (Au), or Cu for Ag. Au, Ag, and Cu were the materials chosen with significant plasmonic activity; Fe, Ru, Pt, and Ni were used to make MNPs with minimal plasmonic response.
Two different stoichiometries of STO were synthesized. One, La-doped A-site deficient STO (La0.6Sr0.2Ti0.9Ni0.1O3–x), was exclusively doped with Ni and utilized as powder samples. The other stoichiometry was A-site excess STO (Sr1.07Ti0.93M0.07O3±δ, where M is the dopant) was doped with various metals. These excess perovskites were studied in thin film and powder forms.
A-site excess STO thin films were deposited by pulsed laser deposition on silicon substrates. The as-deposited thin films appeared nanocrystalline or amorphous until the exsolution process was engaged. The exsolution step was studied explicitly for these A-site excess STO thin films where the formation of MNPs occurred not only at or near the thin film surface but also on grain interfaces and in bulk. Moreover, the dopant diffused significantly during the process.
While the size of the template particles depended on the exsolution conditions, the galvanic replacement reaction determined the shapes and sizes of the newly formed MNPs. The replacement time and the form (thin film/powder) of STO influenced the results, both completely replaced particles and partially replaced particles with complex structures were obtained. Additionally, more prolonged galvanic replacement reactions lead to larger particles. In turn, the specific shape of the plasmonic MNPs determined the localized surface plasmon resonance band shape and peak position.
Overall, exsolution leads to well-socketed MNPs, a property seemingly inherited by the MNPs created by galvanic replacement. Well-socketed MNPs are extremely difficult to obtain by any other technique and have a favorable localized surface plasmon resonance peak shift. The PEC response revealed that reducing STO first decreases the material’s response. Reducing it further, however, increases the PEC response significantly. Au MNPs increase the PEC performance until the MNPs reach a specific size and subsequently decrease the PEC performance when growing more prominent. This work highlights the ease by which well-socketed plasmonic MNPs can be created, some impossible to synthesize by another technique, and how different reaction conditions can change the shape and size of the MNPs, ultimately tuning the localized surface plasmon resonance band shape and peak position. The method of exsolution and galvanic replacement reaction was generalized by utilizing different elements, implying that the tuning of catalytic activity depends on the choice of elements and reaction conditions.
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North, Erlend Tiberg; Nilsen, Ola & Hansen, Per-Anders Stensby
(2022).
Quinizarin as Organic Sensitizer in LnF3 Thin Films for Photon Upconversion.
Universitetet i Oslo.
Show summary
This thesis illuminates the opportunities for Quinizarin (Qz) as an organic sensitizer in LnF3 (Ln=Y, Nd, Tm, Yb) thin films for upconversion. Lanthanides show great promise as active materials for upconversion technologies, but struggle with very low absorption and thus, very low efficiency. We attempt to correct this by including a broad band absorber, in our case an organic dye. Atomic layer deposition (ALD) has been used to build the multilayered structures with control of the interatomic separations. The project has been divided into multiple parts, focusing first on Qz as sensitizer and its properties in solid state by ALD growth of Ln2Qz3. The ALD growth of LnF3 thin films was investigated and multilayered structures intended to show upconversion was made. Initial investigations of Qz show that as a dispersed molecule, its luminescence is heavily influenced by its environment, but indicates it could function as a sensitizer. When combined with Ln(thd)3 as a precursor in ALD growth, it shows exceptionally good growth with high growth rate, as well as high optical absorption. The growth and structure of LnF3 thin films using NH4F as fluorine source has been characterized using quartz crystal microbalance (QCM), with results indicating similar type of growth among all the tested lanthanides, apart for Nd, which proved more challenging. Uniform film with growth rates of around 0.6 Å/cycle were achieved, and NH4F has been proven a good fluorine source in LnF3 systems using Ln(thd)3. Qz has been successfully incorporated into these films with high absorption for high Qz-content, as characterized by using ultraviolet, visible and near infrared spectroscopy (UV-Vis). However, the films were not luminescent, as aimed for, proving that there is more work to be done to understand the quenching mechanisms involved. The upconversion structure itself has been investigated by growing and investigating multilayers of YbF3 with Nd3+ and Tm3+. Using cathodoluminescence (CL) both ions have been shown incorporated in the structure. The system shows different emission intensities depending on ion distance, with 0.8 nm being the most optimal for CL signal.
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Kvalvik, Julie Nitsche; Nilsen, Ola & Hansen, Per-Anders Stensby
(2021).
Design and deposition of CaMoO4 as host for solar down - converters.
Universitetet i Oslo, Det matematisk-naturvitenskapelige fakultet.
ISSN 1501-7710.
2021(2398).
Show summary
Silicon solar cells are approaching their maximum theoretical efficiency. They can still be improved by adapting the sunlight using a pair of light-scissors as down-converters. Such scissors cuts the light into energy packets better suited for the silicon solar cell. Popular down-converters are based on pairs of lanthanides carefully distributed in an absorbing host material. However, synthesizing such materials is challenging. For the process to be efficient, the distance between the lanthanides must be carefully controlled within a nanometer and too much of the lanthanides will also reduce the efficiency.
In the current work we have explored CaMoO4 doped with Pr3+/Yb3+ as a down-converter, using atomic layer deposition (ALD) as the synthesis tool. ALD allows spatial control of the lanthanide dopants, but combining binary ALD-processes to make complex oxides, requires many parameters to be tuned. To ease the tuning, Design of Experiments (DoE) has been used. A new compatible process for deposition of MoOx had to be developed to achieve the goal. As serendipity, this process also showed an area-selective behaviour, which is very rare to observe (Figure 1). Finally, CaMoO4: Pr3+ / Yb3+ was successfully synthesized, and we found that we could use ALD to control its optical properties.
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Sørensen, Silje Holm; Nilsen, Ola & Hansen, Per-Anders Stensby
(2020).
Organic Sensitization in Lanthanide Fluoride Nanostructures for Upconversion.
Universitetet i Oslo.
Show summary
The objective of this thesis is to make organic sensitized upconversion thin films for application on photovoltaic and photocatalytic devices. Upconversion is a light conversion process where two photons of low energy come together to form one photon of higher energy. Using this technique, the light from the sun can be modified to correlate with the bandgaps of for example solar cells. This could potentially increase the efficiencies of the devices drastically. To ensure an efficient upconversion process, organic dyes can be implemented into the system. Organic dyes are good absorbers and can therefore work as sensitizers, increasing the efficiencies of the upconversion process. We have explored how molecular layer deposition (MLD) can be used to synthesize thin films of such upconversion structures. The work in this project has been twofold with one part focusing on implementation of organic dyes into thin films using MLD and the second part aiming to make an upconversion system. During the first part of the project, we proved that the sublimation temperatures of perylenes, a group of large organic dyes are highly dependent on their intramolecular forces. We identified that the perylene FA5 with a molecular mass of 985.12 g/mol still is suitable as a precursor for MLD growth despite its large molecular mass. This is a significant expansion in use of heavy molecules for MLD, as compared to prior experience. Furthermore, perylenes have successfully been implemented into thin films using β-diketonates Ln(thd)3as cation precursors. The perylene based films have been made both with and without using the amino acid glycine as a linker between the Ln and the perylene. The films containing glycine have remarkably higher growth ratesthan thosewithout, due to formation of a Ln-Glycine phase during growth. The growth dynamics have been explored by quartz crystal microbalance (QCM) and the optical properties by UV-Vis, showing stronger absorbing properties in the films deposited without linker.All perylene based films formed structuresclose to the stoichiometryLn2Perylene3.
The upconversion properties were explored through depositions of lanthanide-fluoride thin films with Tm3+and Nd3+doped in an YbF3matrix. Both dopants were successfully implemented as both Tm3+and Nd3+ luminescence can be seen from cathodoluminescence (CL) measurements,indicating promising luminescent properties. Growth of YbF3 was explored using NH4F as the chosen fluoride precursor and Yb(thd)3 as Yb precursor. We obtained growth rates of approximately 0.2 Å/cycle with good reproducibility, making it a good system.
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