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- Stashans, Arvids, et al.
(författare)
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Theoretical study of lithium intercalation in rutile and anatase
- 1996
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 53:1, s. 159-170
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Motivated by recent developments concerning coloration and energy storage in lithium intercalated nanostructural TiO2, quantum chemical Hartree-Fock calculations have been carried out to study lithium atom intercalation in rutile and anatase. Equilibrium geometries and effective atomic charges were obtained for the rutile (110) and anatase (101) clean surfaces. Li-induced local one-electron energy levels were found in the gap between the upper valence band and the conduction band and could be attributed to Ti3+ states. The absorption energies obtained are compared with available experimental data. The equilibrium positions of the Li atom and its surrounding host atoms have been calculated for both structures. The results predict a higher possibility of lithium intercalation in the anatase structure than in rutile.
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| 3. |
- Beermann, Niclas, et al.
(författare)
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Photoelectrochemical studies of oriented nanorod thin films of hematite
- 2000
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Ingår i: JOURNAL OF THE ELECTROCHEMICAL SOCIETY. - : ELECTROCHEMICAL SOC INC. - 0013-4651. ; 147:7, s. 2456-2461
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Tidskriftsartikel (refereegranskat)abstract
- Thin films consisting of nanorods of hematite (alpha-Fe2O3) with controlled orientation onto transparent conductive glass substrates have been tested as photoelectrochemical cells. These films allow a more efficient transport and collection of photogenera
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| 4. |
- Ding, Bangfu, et al.
(författare)
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Oxygen Vacancy Effect on Photoluminescence Properties of Self-Activated Yttrium Tungstate
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:44, s. 25633-25642
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Tidskriftsartikel (refereegranskat)abstract
- A series of single-phase yttrium tungstate powders were synthesized through solid-state reaction under air or argon atmosphere. All powders showed broad band emission in the visible light region, and the argon-calcined samples presented strong near-infrared luminescence. Moreover, the long-wave excitation bands peaking at 340, 378, 380, 490, and 523 nm depended critically on the calcination atmosphere and temperature. The emergence of these new excitation bands was ascribed to different oxygen vacancy concentrations with the analysis of the first-principle calculation, Raman and X-ray absorption fine structure spectra. The oxygen vacancies caused the reduction of the average coordination number of tungsten, and the position of the localized energy band changed with the oxygen vacancy concentration. Finally, a schematic photoluminescence excitation model was proposed via anion and cation charge transfer. The obtained results promise to be very useful in interpreting self-activated tungstate luminescence mechanism. They can also serve as guide line for tuning the luminescence performance of yttrium tungstate and related materials.
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| 5. |
- Fredin, Kristofer, et al.
(författare)
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Effect on Cell Efficiency following Thermal Degradation of Dye-Sensitized Mesoporous Electrodes Using N719 and D5 Sensitizers
- 2009
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:43, s. 18902-18906
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Tidskriftsartikel (refereegranskat)abstract
- This work examines the comparative durability of two common dyes at temperatures that may be experienced during fabrication of dye-sensitized solar cells (DSCs) such as through the application of thermoplastics for encapsulation or the use of a molten solid-state hole conductor. Dye-sensitized electrodes were heated in an atmosphere of air or nitrogen and thereafter used as working electrodes in DSCs. Electrodes sensitized with N719 appeared more sensitive to thermal degradation than electrodes sensitized with D5, although absorbance measurements suggest similar first-order degradation rates for the two dyes. Intensity modulated photovoltage spectroscopy and intensity modulated photocurrent spectroscopy were used to measure the effect of heating on electron lifetime and transport. It was found that the electron diffusion length may.. be as low as 10% for heated samples, compared to that of the unheated counterpart, and therefore, we assess recombination as an additional efficiency limiting process in our experiments.
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| 8. |
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| 9. |
- Greijer, Helena, et al.
(författare)
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Environmental aspects of electricity generation from a nanocrystalline dye-sensitized solar cell system
- 2001
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Ingår i: Renewable Energy. ; 23, s. 27-39
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Tidskriftsartikel (refereegranskat)abstract
- A Life Cycle Assessment, LCA, of a nanocrystalline dye sensitized solar cell (ncDSC) system has been performed, according to the ISO14040 standard. In brief, LCA is a tool to analyse the total environmental impact of a product or system from cradle to grave. Six different weighing methods were used to rank and select the significant environmental aspects to study further. The most significant environmental aspects according to the weighing methods are emission of sulphur dioxide and carbon dioxide. Carbon dioxide emission was selected as the environmental indicator depending on the growing attention on the global warming effect. In an environmental comparison of electricity generation from a ncDSC system and a natural gas/combined cycle power plant, the gas power plant would result in 450 g CO2/kWh and the ncDSC system in between 19–47 g CO2/kWh. The latter can be compared with 42 g CO2/kWh, according to van Brummelen et al. “Life Cycle Assessment of Roof Integrated Solar Cell Systems, (Report: Department of Science, Technology and Society, Utrecht University, The Netherlands, 1994)” for another thin film solar cell system made of amorphous silicon. The most significant activity/component contributing to environmental impact over the life cycle of the ncDSC system is the process energy for producing the solar cell module. Secondly comes the components; glass substrate, frame and junction box. The main improvement from an environmental point of view of the current technology would be an increase in the conversion efficiency from solar radiation to electricity generation and still use low energy demanding production technologies. Also the amount of material in the solar cell system should be minimised and designed to maximise recycling.
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