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| 3. |
- Coll, M., et al.
(author)
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Towards Oxide Electronics: a Roadmap
- 2019
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In: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 482, s. 1-93
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Journal article (peer-reviewed)abstract
- At the end of a rush lasting over half a century, in which CMOS technology has been experiencing a constant and breathtaking increase of device speed and density, Moore’s law is approaching the insurmountable barrier given by the ultimate atomic nature of matter. A major challenge for 21st century scientists is finding novel strategies, concepts and materials for replacing silicon-based CMOS semiconductor technologies and guaranteeing a continued and steady technological progress in next decades. Among the materials classes candidate to contribute to this momentous challenge, oxide films and heterostructures are a particularly appealing hunting ground. The vastity, intended in pure chemical terms, of this class of compounds, the complexity of their correlated behaviour, and the wealth of functional properties they display, has already made these systems the subject of choice, worldwide, of a strongly networked, dynamic and interdisciplinary research community. Oxide science and technology has been the target of a wide four-year project, named Towards Oxide-Based Electronics (TO-BE), that has been recently running in Europe and has involved as participants several hundred scientists from 29 EU countries. In this review and perspective paper, published as a final deliverable of the TO-BE Action, the opportunities of oxides as future electronic materials for Information and Communication Technologies ICT and Energy are discussed. The paper is organized as a set of contributions, all selected and ordered as individual building blocks of a wider general scheme. After a brief preface by the editors and an introductory contribution, two sections follow. The first is mainly devoted to providing a perspective on the latest theoretical and experimental methods that are employed to investigate oxides and to produce oxide-based films, heterostructures and devices. In the second, all contributions are dedicated to different specific fields of applications of oxide thin films and heterostructures, in sectors as data storage and computing, optics and plasmonics, magnonics, energy conversion and harvesting, and power electronics.
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| 4. |
- Hagvall, Lina, 1978, et al.
(author)
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Assessment of cross-reactivity of new less sensitizing epoxy resin monomers in epoxy resin-allergic individuals
- 2016
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In: Contact Dermatitis. - : Wiley. - 0105-1873. ; 75:3, s. 144-150
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Journal article (peer-reviewed)abstract
- BackgroundMeasures to prevent occupational exposure to epoxy resins, including education, medical examination, and voluntary agreements between employers and workers, have not been effective enough to protect against skin sensitization. Therefore, alternatives to the major epoxy resin haptens that have been found to be less sensitizing in the local lymph node assay have been developed. ObjectivesTo study the cross-reactivity of two newly designed epoxy resin monomers, with decreased skin-sensitizing potency and good technical properties as compared with diglycidyl ether of bisphenol A (DGEBA), in subjects with known contact allergy to epoxy resin of DGEBA type. Patients and MethodsEleven individuals with previous positive patch test reactions to epoxy resin of DGEBA participated in the study. The two alternative epoxy resin monomers were synthesized and patch tested in dilution series in parallel with epoxy resin of DGEBA from the baseline series (containing 92% DGEBA). ResultsAll participants reacted to epoxy resin of DGEBA on retesting. Three participants reacted to monomer 1. No reactions were seen to monomer 2. ConclusionsThe alternative monomers studied showed little or no cross-reactivity with epoxy resin of DGEBA. Decreasing the risk of sensitization by using less sensitizing compounds is important, as contact allergy to epoxy resins is common in spite of thorough preventive measures.
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| 5. |
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| 6. |
- Horling, J, et al.
(author)
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Distribution and genetic heterogeneity of Puumala virus in Sweden
- 1996
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In: JOURNAL OF GENERAL VIROLOGY. - : SOC GENERAL MICROBIOLOGY. - 0022-1317. ; 77, s. 2555-2562
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Journal article (other academic/artistic)abstract
- Small mammals trapped in Sweden were analysed for specific antibody responses against three hantavirus serotypes and for the presence of viral antigen. To determine the genetic identity of viral RNA in lungs of seropositive bank voles (Clethrionomys glare
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| 7. |
- Hultborn, Ragnar, 1946, et al.
(author)
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Efficacy of pamidronate in breast cancer with bone metastases: a randomized, double-blind placebo-controlled multicenter study
- 1999
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In: Anticancer Res. - 0250-7005. ; 19:4C, s. 3383-92
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Journal article (peer-reviewed)abstract
- PURPOSE: To evaluate the efficacy of pamidronate 60 mg i.v. q 4 weeks in women with advanced breast cancer with skeletal metastases. PATIENTS AND METHODS: 404 woman with skeletal metastases from breast cancer in Sweden and Norway were included in a randomized, placebo-controlled, multicenter study. Except for the study medication, other palliative treatment was chosen at the discretion of the physician. Skeletal related events, i.e. increased pain, treatment of hypercalcemia, pathologic fractures of long bones or pelvis, paralyses due to vertebral compression, palliative radiotherapy for skeletal metastases, surgery on bone and change of antitumor therapy were recorded every third month as well as a self-estimated pain-score using visual Analog Scales and analgesic consumption. RESULTS: There was a significantly increased time to progression of pain (p < 0.01), to hypercalcemic events (p < 0.05) as well as for the cumulative number of skeletal related events (p < 0.01) in favor for the pamidronate group. No statistically significant reduction of pathologic fractures of long bones or pelvis, or pareses due to vertebral compression occurred. No statistically significant differences were found for the need of radiotherapy and surgery on bone. The pamidronate group faired better regarding performance status (p < 0.05). There was a statistically not significant lower consumption of opioid analgesics in the pamidronate group (p = 0.14). CONCLUSION: Pamidronate 60 mg i.v. q 4 weeks reduces skeletal events and improves the quality of life in women with bone metastases from breast cancer.
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| 11. |
- NETTELBLAD, B, et al.
(author)
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APPROXIMATE DETERMINATION OF SURFACE CONDUCTIVITY IN POROUS-MEDIA
- 1995
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In: JOURNAL OF PHYSICS D-APPLIED PHYSICS. - : IOP PUBLISHING LTD. - 0022-3727. ; 28:10, s. 2037-2045
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Journal article (peer-reviewed)abstract
- We have studied the fluid permeability and the electrical conduction in artificially made impregnated sandstones in order to determine the surface conductivity approximately. The electrical conductivity of the impregnated porous medium is not proportional
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| 15. |
- Abrikosov, IA, et al.
(author)
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Order-N Green's function technique for local environment effects in alloys
- 1996
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In: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. ; 76:22, s. 4203-4206
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Journal article (other academic/artistic)abstract
- We have developed a new approach to the calculations of ground state properties of large crystalline systems with arbitrary atomic configurations based on a Green's function technique in conjunction with a self-consistent effective medium for the underlyi
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| 17. |
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| 18. |
- Delaine, Tamara, 1981, et al.
(author)
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A structure activity relationship study of geranial derivatives
- 2012
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In: Contact Dermatitis 11th congress of the European society of contact dermatitis (ESCD) 13-16 june 2012, Malmö, Sweden. - : Wiley. ; 66:Suppl. 2
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Conference paper (peer-reviewed)abstract
- Background: Fragrances are common causes of contact allergy. Skin exposure to geranial is frequent since citral (mixture of geranial and neral) is commonly used in fragrances and flavors and is considered as a moderate allergen. Previous studies according to the local lymphnodeassay (LLNA)in micehaverevealed large variations in the sensitizing capacity of different geranial derivatives. Objectives: For a better understanding of these variations, a structure-activity relationship (SAR) study on a series of derivatives of geranial was carried out. Methods: The chemical reactivity of the compounds towards a model peptide was investigated using LC-MS. The adduct formation and the non-reacted peptide depletion were monitored. Adducts formed with model amino acids were investigated and structural determination was performed. Additional derivatives were synthesized and their sensitization potencies were evaluated in relation to their physicochemical and reactivity properties. Results: Most of the derivatives were shown to bind covalently to the cysteine residue of the model peptide. The percentage of depletion of the non-reacted peptide ranged from 0% to 100% after 24 hr, constant rate of depletion revealed a large difference between the fastest and lowest reacting derivatives. These resultswere congruent with the skin sensitization potencies obtained with the LLNA. Conclusions: A good correlation between the reactivity and the sensitizing potency was observed. Small changes in the chemical structure of geranial result in significant differences in sensitizing capacity and chemical reactivity. Conflicts of interest: The authors have declared no conflicts.
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| 19. |
- Delaine, Tamara, 1981, et al.
(author)
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Epoxyalcohols: bioactivation and conjugation required for skin sensitization.
- 2014
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In: Chemical research in toxicology. - : American Chemical Society (ACS). - 1520-5010 .- 0893-228X. ; 27:10, s. 1860-70
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Journal article (peer-reviewed)abstract
- Allylic alcohols, such as geraniol 1, are easily oxidized by varying mechanisms, including the formation of both 2,3-epoxides and/or aldehydes. These epoxides, aldehydes, and epoxy-aldehydes can be interconverted to each other, and the reactivity of them all must be considered when considering the sensitization potential of the parent allylic alcohol. An in-depth study of the possible metabolites and autoxidation products of allylic alcohols is described, covering the formation, interconversion, reactivity, and sensitizing potential thereof, using a combination of in vivo, in vitro, in chemico, and in silico methods. This multimodal study, using the integration of diverse techniques to investigate the sensitization potential of a molecule, allows the identification of potential candidate(s) for the true culprit(s) in allergic responses to allylic alcohols. Overall, the sensitization potential of the investigated epoxyalcohols and unsaturated alcohols was found to derive from metabolic oxidation to the more potent aldehyde where possible. Where this is less likely, the compound remains weakly or nonsensitizing. Metabolic activation of a double bond to form a nonconjugated, nonterminal epoxide moiety is not enough to turn a nonsensitizing alcohol into a sensitizer, as such epoxides have low reactivity and low sensitizing potency. In addition, even an allylic 2,3-epoxide moiety is not necessarily a potent sensitizer, as shown for 2, where formation of the epoxide weakens the sensitization potential.
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| 20. |
- Delaine, Tamara, 1981, et al.
(author)
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Structure-Activity Relationship between the in Vivo Skin Sensitizing Potency of Analogues of Phenyl Glycidyl Ether and the Induction of Nrf2-Dependent Luciferase Activity in the KeratinoSens in Vitro Assay.
- 2011
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In: Chemical research in toxicology. - : American Chemical Society (ACS). - 1520-5010 .- 0893-228X. ; 24:8, s. 1312-8
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Journal article (peer-reviewed)abstract
- Because of regulatory constraints and ethical considerations, research on alternatives to animal testing to predict the skin sensitization potential of novel chemicals has become a high priority. Ideally, these alternatives should not only predict the hazard of novel chemicals but also rate the potency of skin sensitizers. Currently, no alternative method gives reliable potency estimations for a wide range of chemicals in differing structural classes. Performing potency estimations within specific structural classes has thus been proposed. Detailed structure-activity studies for the in vivo sensitization capacity of a series of analogues of phenyl glycidyl ether (PGE) were recently published. These studies are part of an investigation regarding the allergenic activity of epoxy-resin monomers. Here we report data on the same chemicals in the KeratinoSens in vitro assay, which is based on a stable transgenic keratinocyte cell line with a luciferase gene under the control of an antioxidant response element. A strong correlation between the EC3 values in the local lymph node assay (LLNA) and both the luciferase-inducing concentrations and the cytotoxicity in the cell-based assay was established for six analogues of PGE. This correlation allowed the potency in the LLNA of two novel structurally closely related derivatives to be predicted by read-across with errors of 1.4- and 2.6-fold. However, the LLNA EC3 values of two structurally different bifunctional monomers were overpredicted on the basis of this data set, indicating that accurate potency estimation by read-across based on in vitro data might be restricted to a relatively narrow applicability domain.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Enckell, P H, et al.
(author)
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The dispersal pattern of an anthropochorous species: Genetic variation in populations of Lumbricus terrestris L. (Lumbricidae) in the Faroe Islands
- 1986
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In: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 104:2, s. 253-261
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Journal article (peer-reviewed)abstract
- Ten populations of the anthropochorous Lumbricus terrestris L. (Lumbricidae) from six islands in the Faroes were scored for enzyme variation by electrophoresis. The allele frequencies were analyzed by cluster analysis and information entropy relationships. There was a significant heterogeneity in allele frequencies among the samples. Four groups could be distinguished in the cluster analysis of which one was larger (at least five sites); two sites were defined as outliers. Information entropy showed that the allele frequency data were structured differently over the sites and that the most non-random site was also one of the outliers in the cluster space. The main group in the cluster analysis also forms a geographically central group in the islands. These results are discussed against the known colonization history of the Faroes. It is concluded that the genetic variation pattern does not indicate any single point of invasion of L. terrestris into the islands. Rather, it shows that former and present-day communications between the islands are responsible for similarities and dissimilarities in genetic variation in the L. terrestris populations.
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| 27. |
- Erdélyi, Máté, et al.
(author)
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Chemistry and folding of photomodulable peptides : stilbene and thioaurone-type candidates for conformational switches
- 2008
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In: Organic and biomolecular chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 6:23, s. 4356-4373
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Journal article (peer-reviewed)abstract
- Optimized synthetic strategies for the preparation of photoswitchable molecular scaffolds based on stilbene or on thioaurone chromophores and their conformationally directing properties, as studied by computations and by NMR spectroscopy, are addressed. For the stilbene peptidomimetics 1, 2 and 3, the length of connecting linkers between the chromophore and the peptide strands was varied, resulting in photochromic dipeptidomimetics with various flexibility. Building blocks of higher rigidity, based on para-substituted thioaurone ( 4 and 6) and meta-substituted thioaurone chromophores ( 5 and 7) are shown to have a stronger conformationally directing effect. Design, synthesis, theoretical and experimental conformational analyses are presented.
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| 28. |
- Foberg, U, et al.
(author)
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Viral haemorrhagic fever in Sweden : experiences from management of a case.
- 1991
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In: Scandinavian Journal of Infectious Diseases. - 0036-5548 .- 1651-1980. ; 23:2, s. 143-151
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Journal article (peer-reviewed)abstract
- The first recognized case in Scandinavia with potential man to man transmission of viral haemorrhagic fever occurred in Linköping, Sweden, in January 1990. Following a visit to Kenya a 21-year-old male student suffered a very severe illness including extremely prolonged high grade fever, rash, disseminated intravascular coagulation with thrombocytopenia and severe bleedings. This necessitated one month of intensive care support including respirator treatment. The patient was discharged after 2 1/2 months in good condition, with a partial femoral nerve paresis. About 100 medical personnel were exposed to aerosol or blood before a strict containment regimen was established. No secondary cases occurred.
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| 30. |
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| 31. |
- Granqvist, Claes Göran, et al.
(author)
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Electrochromic foil-based devices : Optical transmittance and modulation range, effect of ultravioled irradiation, and quality assessment by 1/f current noise
- 2008
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 516:17, s. 5921-5926
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Journal article (peer-reviewed)abstract
- We introduce electrochromic (EC) technology for modulating the transmittance of visible light and solar radiation in window apertures, with focus on recent work on foil-type devices embodying sputter deposited WO3 and NiO films joined by a polymer electrolyte. The purpose of this paper is to present a number of new and preliminary results showing that (i) double-sided antireflection coatings based on dip coating can enhance the transmittance significantly, (ii) tandem foils can yield a ratio between bleached-state and colored-state transmittance exceeding fifty, (iii) solar irradiance onto the EC device can enhance its charge insertion dynamics and thereby its optical modulation, and (iv) electromagnetic noise spectroscopy may serve as quality assessment of EC devices.
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| 32. |
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| 33. |
- Hagvall, Lina, 1978, et al.
(author)
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Can the epoxides of cinnamyl alcohol and cinnamal show new cases of contact allergy?
- 2018
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In: Contact dermatitis. - : Wiley. - 1600-0536 .- 0105-1873. ; 78:6, s. 399-405
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Journal article (peer-reviewed)abstract
- Cinnamyl alcohol is considered to be a prohapten and prehapten with cinnamal as the main metabolite. However, many individuals who are allergic to cinnamyl alcohol do not react to cinnamal. Sensitizing epoxides of cinnamyl alcohol and cinnamal have been identified as metabolites and autoxidation products of cinnamyl alcohol.To investigate the clinical relevance of contact allergy to epoxycinnamyl alcohol and epoxycinnamal.Irritative effects of the epoxides were investigated in 12 dermatitis patients. Epoxycinnamyl alcohol and epoxycinnamal were patch tested in 393 and 390 consecutive patients, respectively. In parallel, cinnamyl alcohol and cinnamal were patch tested in 607 and 616 patients, respectively.Both epoxides were irritants, but no more positive reactions were detected than when testing was performed with cinnamyl alcohol and cinnamal. Late allergic reactions to epoxycinnamyl alcohol were observed. In general, patients with late reactions showed doubtful or positive reactions to cinnamal and fragrance mix I at regular patch testing.The investigated epoxides are not important haptens in contact allergy to cinnamon fragrance. The high frequency of fragrance allergy among patients included in the irritancy study showed the difficulty of suspecting fragrance allergy on the basis of history; patch testing broadly with fragrance compounds is therefore important.
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| 34. |
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| 35. |
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| 36. |
- Henk, J, et al.
(author)
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Magnetic structure and anisotropy of ultra-thin Ni films on Cu(001)
- 1998
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In: PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES. - : TAYLOR & FRANCIS LTD. - 0141-8637. ; 78:5-6, s. 585-589
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Journal article (other academic/artistic)abstract
- Both magnetic structure and magnetic anisotropy energy (MAE) are calculated for fee and fct Ni films on Cu(001) for thicknesses from I to 10 monolayers (ML). The transition from in-plane to perpendicular anisotropy can be attributed to the volume contribu
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| 37. |
- Henk, J, et al.
(author)
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Magnetism and anisotropy of ultrathin Ni films on Cu(001)
- 1999
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In: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMERICAN PHYSICAL SOC. - 0163-1829. ; 59:14, s. 9332-9341
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Journal article (other academic/artistic)abstract
- Both magnetic structure and magnetic-anisotropy energies are calculated for cubic and tetragonal Ni films on Cu(001) for thicknesses from 1 to 10 monolayers. The magnetic reorientation transition from in-plane to perpendicular anisotropy can be attributed
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| 38. |
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| 39. |
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| 40. |
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| 41. |
- HORLING, J, et al.
(author)
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Detection and subsequent sequencing of Puumala virus from human specimens by PCR
- 1995
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In: Journal of clinical microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 33:2, s. 277-282
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Journal article (peer-reviewed)abstract
- A sensitive method based on PCR was developed for the detection of Puumala virus (PUU) in human samples. The assay was found to be specific for PUU-like strains and distinguished between these and hantaviruses of other serotypes. The detection limit was found to be 10(-5) focus-forming units. Clinical samples were collected from patients with nephropathia epidemica in Sweden and western Russia. Five whole blood samples collected from patients in Russia with the acute phase of disease were found to be positive by the PCR. All samples were negative for PUU antigen when examined by enzyme-linked immunosorbent assay. Virus isolation on Vero E6 cells from several of the acute-phase samples, including the 5 PCR-positive samples, was not successful. The amplified samples were subjected to direct nucleic acid sequencing for confirmation of identity. The sequences differed from each other and were closely related to the Russian bank vole isolate CG-1820, thereby indicating the origin of nephropathia epidemica. The PCR was used for amplification and subsequent nucleotide sequencing of eight PUU-like isolates with different geographic origins. The Swedish strains were more closely related to the Finnish PUU prototype strain, Sotkamo, than to the Russian isolates. Interestingly, a Belgian isolate, CG-13891, differed markedly from all other PUU strains.
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| 47. |
- Johansson, Malin B., et al.
(author)
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Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations
- 2013
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In: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 25:20, s. 205502-
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Journal article (peer-reviewed)abstract
- The optical and electronic properties of nanocrystalline WO3 thin films prepared by reactive dc magnetron sputtering at different total pressures (P-tot) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low P-tot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies E-g approximate to 3.1 eV, which increase with increasing P-tot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic delta-WO3, and monoclinic gamma- and epsilon-WO3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The delta-WO3 and gamma-WO3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (>3 eV) and allowed transitions (>3.8 eV). The calculations show that E-g in epsilon-WO3 is higher than in the delta-WO3 and gamma-WO3 phases, which provides an explanation for the P-tot dependence of the optical data.
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| 48. |
- Johansson, Malin B., et al.
(author)
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Optical properties of nanocrystalline WO3 and WO3-x thin films prepared by DC magnetron sputtering
- 2014
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In: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 115:21, s. 213510-
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Journal article (peer-reviewed)abstract
- The optical properties of tungsten trioxide thin films prepared by DC magnetron sputtering, withdifferent oxygen vacancy (Vo) concentration, have been studied by spectrophotometry andphotoluminescence (PL) emission spectroscopy. Absorption and PL spectra show that the filmsexhibit similar band gap energies, Eg 2.9 eV. The absorption spectra of the films show twopronounced absorption bands in the near-infrared region. One peak (P1) is located atapproximately 0.7 eV, independent of Vo concentration. A second peak (P2) shifts from 0.96 eV to1.16 eV with decreasing Vo concentration. Peak P1 is assigned to polaron absorption due totransitions between tungsten sites (W5þ!W6þ), or an optical transition from a neutral vacancystate to the conduction band, Vo0!W6þ. The origin of peak P2 is more uncertain but may involveþ1 and þ2 charged vacancy sites. The PL spectra show several emission bands in the range 2.07 to3.10 eV in the more sub-stoichiometric and 2.40 to 3.02 eV in the less sub-stoichiometric films.The low energy emission bands agree well with calculated optical transition energies of oxygenvacancy sites, with dominant contribution from neutral and singly charged vacancies in the lesssub-stoichiometric films, and additional contributions from doubly charged vacancy sites in themore sub-stoichiometric films.
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| 49. |
- Johansson, Malin B, 1972-, et al.
(author)
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Porous Fractals of MAPbI3 Perovskite : Characterization of Crystal Grain Formation by Irreversible Diffusion-Limited Aggregation
- 2018
-
Conference paper (peer-reviewed)abstract
- Isopropanol solution based methylammonium lead triiodide (MAPbI3) is studied during the crystallization process. The crystal growth starts in an unstable suspension far from equilibrium by forming different dendritic patterns and terminates with aggregation of stable cubic crystalline grains into fractal clusters. Using transmission electron microscopy (TEM), the time evolution of a newly mixed suspension was studied over a period of two weeks at room temperature and a sequence of the morphological changes was observed. The crystallization process started with single dendritic growth exhibiting branches at 90 degrees angles to one another. After 4 hours, a multi-dendritic growth pattern and a transformation into small crystalline quantum dots were observed. After a week, clusters of crystal grains were formed into a fractal pattern and these patterns appear to be stable also during the second week. Electron and x-ray diffraction revealed the crystallinity of the quantum dots and the clusters of micrometer-sized crystals. Scanning transmission electron microscope (STEM) together with energy dispersive X-ray spectroscopy (EDS) showed that newly formed large grains, from a one hour old solution, displayed a core-shell structure with higher percentage of Pb atoms as compared to iodine at the surface. In the inner core of the grains the percentage of iodine was slightly higher. The electron diffraction (ED) scan over the newly formed grains revealed a polycrystalline surface whereas the inner part had a single crystal pattern. The same solution, now one-week-old, contained grains with only single crystal patterns in the ED scan and showed no core-shell character or polycrystalline surface. The measured percentage of iodine atoms compared to lead was 2:1 throughout the cross section, which is a quantitative value within the measurement. It can be concluded from these measurements that the suspension approaches higher crystallinity of the perovskite grains in an irreversible process, where the perovskite grains are insoluble in isopropanol. The perovskite material has also been characterized with scanning electron microscopy (SEM) and photoluminescence (PL) mapping where both techniques showed a very porous crystalline material. The PL mapping revealed two peaks at 730 and 760 nm for a thin film spin coated from a newly mixed solution, while a film deposited from a one week old solution showed three peaks, the last one at 830 nm. Because of the high crystallinity, it is suggested that all three peaks are due to band-to-band transitions and not due to localized states. These data will be analyzed further; however, the results contain information of the content of quantum dots versus larger crystals, as well as displaying emission intensity variations at different positions of the grains. The purpose with this project is to understand these phenomena of crystal growth. A new mesoporous perovskite material has been designed for optoelectronic purposes.
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| 50. |
- Johansson, Malin B, et al.
(author)
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Structural and optical properties of visible active photocatalytic WO3 thin films prepared by reactive dc magnetron sputtering
- 2012
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In: Journal of Materials Research. - : Springer Science and Business Media LLC. - 0884-2914 .- 2044-5326. ; 27:24, s. 3130-3140
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Journal article (peer-reviewed)abstract
- Nanostructured tungsten trioxide films were prepared by reactive dc magnetron sputteringat different working pressures P-tot = 1-4 Pa. The films were characterized by scanning electron microscopy, x-ray diffraction, Rutherford backscattering spectroscopy, Raman spectroscopy, and ultraviolet-visible spectrophotometry. The films were found to exhibit predominantly monoclinic structures and have similar band gap, E-g approximate to 2.8 eV, with a pronounced Urbach tail extending down to 2.5 eV. At low P-tot, strained film structures formed, which were slightly reduced and showed polaron absorption in the near-infrared region. The photodegradation rate of stearic acid was found to correlate with the stoichiometry and polaron absorption. This is explained by a recombination mechanism, whereby photoexcited electron-hole pairs recombine with polaron states in the band gap. The quantum yield decreased by 50% for photon energies close to E-g due to photoexcitations to band gap states lying below the O-2 affinity level.
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