| 1. |
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| 2. |
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| 3. |
- Bandara, T M W J, 1968, et al.
(författare)
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Binary counter ion effects and dielectric behavior of iodide ion conducting gel-polymer electrolytes for high-efficiency quasi-solid-state solar cells
- 2020
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 22:22, s. 12532-12543
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Tidskriftsartikel (refereegranskat)abstract
- A series of highly efficient quasi-solid-state dye-sensitized solar cells (DSCs) is prepared by harnessing the binary cation effect and positive effects of the selected performance enhancers of gel-polymer electrolytes. The new electrolyte is composed of polyacrylonitrile polymer, tetra-hexylammonium iodide (Hex(4)NI) and KI binary salts as well as 4-tertbutylpyridine and 1-butyl-3-methylimidazolium iodide performance enhancers. The charge transport in the series of electrolytes is thermally activated and, accordingly, the temperature dependence of conductivity follows the VTF behavior. The enhancement of conductivity is observed with an increasing mass fraction of KI and decreasing mass fraction of Hex(4)NI, while the total mass fraction of salts in the electrolyte is kept unchanged. The highest conductivity of 3.74 mS cm(-1)at ambient temperature is shown by the sample containing KI only (without Hex(4)NI) at all the temperatures. The effects of dielectric polarization of the electrolytes are studied by analyzing the frequency dependence of the real and the imaginary parts of the AC conductivity in detail. Appropriate and reproducible cell construction are assured by efficiencies of above 5% exhibited by all the quasi-solid-state DSCs assembled using double-layered TiO(2)photo-electrodes and the new electrolyte series. Besides, highlighting the mixed cation effect, the cells with mixed salts exhibited efficiencies greater than 6%. An impressively high efficiency of 7.36% was shown by the DSC prepared with electrolyte containing 75 wt% KI and 25 wt% Hex(4)NI. This study reveals that the salt combination of KI and Hex(4)NI, which has not been reported before, is a suitable binary iodide salt mixture to prepare highly efficient DSCs. The replacement of tetra-hexylammonium ions by K(+)ions improves the charge transport in the electrolyte; however, the best solar cell performance is shown by the mixed salt system with 75 wt% KI and 25 wt% Hex(4)NI, which is not the highest conductivity composition. Therefore, the exhibited high efficiency of 7.36% is evidently due to the binary cation effect.
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| 4. |
- Bandara, T M W J, 1968, et al.
(författare)
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Combined effect of alkaline cations and organic additives for iodide ion conducting gel polymer electrolytes to enhance efficiency in dye sensitized solar cells
- 2017
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 252, s. 208-214
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Tidskriftsartikel (refereegranskat)abstract
- Iodide ion conducting electrolytes are intensively studied as effectual electrolytes for dye-sensitized solar cells (DSSCs). However, the nature and concentration of the counter-ion (cation) in the electrolyte exert a profound influence on the performance of the thin film meso-porous TiO2 based DSSCs. A series of gel electrolytes containing the alkaline iodides LiI, NaI, KI, RbI and CsI and polyacrylonitrile (PAN) were fabricated together with the non-volatile plasticizers ethylene carbonate (EC) and propylene carbonate (PC). A similar series was fabricated with the inclusions of performance enhancers (additives) tetrapropylammonium iodide (Pr4NI), the ionic liquid 1-methyl-3-propyl imidazolium iodide (MPII) and 4-tert-butylpyridine (4TBP). The ionic conductivity of the electrolytes was studied in order to investigate its dependence on the nature of the alkaline cation in presence or absence of additives. The conductivities were higher for the electrolytes with the larger cations, namely K+, Rb+ and Cs+. A significant conductivity enhancement was observed in presence of the additives, and this effect was especially noticeable for samples with the smaller cations. The highest conductivity for electrolytes with additives, 3.96 mS cm(-1) at 25 degrees C, is exhibited by KI containing samples. (C) 2017 Elsevier Ltd. All rights reserved.
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| 5. |
- Bandara, T M W J, 1968, et al.
(författare)
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Conductivity behaviour in novel quasi-solid-state electrolyte based on polyacrylonitrile and tetrahexylammonium iodide intended for dye sensitized solar cells
- 2013
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Ingår i: Journal of the National Science Foundation of Sri Lanka. - : Sri Lanka Journals Online (JOL). - 1391-4588 .- 2362-0161. ; 41:3, s. 175-184
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Tidskriftsartikel (refereegranskat)abstract
- The conduction of iodide ions in gel polymer electrolytes and the performance of dye sensitized solar cells containing such an electrolyte can be enhanced by incorporating a salt having a bulky cation. In this work, polyacrylonitrile (PAN) and Hex(4)N(+)I(-) based gel electrolytes with ethylene carbonate and propylene carbonate as plasticizers have been studied. The variation of conductivity and molar conductivity with salt concentration has been discussed in order to understand the mechanism of iodide ion conductivity in this system. Out of the various compositions studied, the electrolyte containing 120 % salt with respect to weight of PAN showed the highest conductivity, 2.0 X 10(-3) Scm(-1) at 25 degrees C and a glass transition at - 102.3 degrees C. The electrolytes exhibit predominantly ionic behaviour and because of the bulky cation a negligible cationic transport is shown. A quasi-solid-state dye sensitized solar cell was fabricated employing the optimized gel electrolyte. This cell showed an energy conversion efficiency of 3.1 % and a short circuit current density of 8.1 mAcm(-2) under irradiation of 1000 Wm(-2).
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| 6. |
- Bandara, T M W J, 1968, et al.
(författare)
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Determination of charge carrier transport parameters in a polymer electrolyte intended for Li-ion batteries using electrochemical impedance analysis
- 2020
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1433-0768 .- 1432-8488. ; 24:5, s. 1207-1216
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Tidskriftsartikel (refereegranskat)abstract
- Solid polymer electrolytes are key components in many electrochemical devices. For an in-depth study of the basic parameters of such electrolytes, we developed a previously proposed method in order to determine the charge carrier density (n), mobility (μ), and diffusion coefficient (D) of ionic conductors using electrochemical impedance analysis. This reinforced method was tested with a composite solid electrolyte based on polyethylene oxide, ethylene carbonate, LiCF3SO3, and alumina filler by analyzing DC conductivity, frequency dependence of AC conductivity, and the complex dielectric function. The results show a clear picture of the temperature dependence of the parameters n, μ, and D; for example, at 20 °C, more than 15% of the total number of ions available in the electrolyte are mobile, and this value decreases with increasing temperature, most probably due to increased ion association in agreement with measurements using other techniques. The increase in ionic conductivity with increasing temperature is thus due to an increased mobility of the ionic species.
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| 7. |
- Bandara, T M W J, 1968, et al.
(författare)
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Efficiency enhancement of dye-sensitized solar cells with PAN:CsI:LiI quasi-solid state (gel) electrolytes
- 2014
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Ingår i: Journal of Applied Electrochemistry. - : Springer Science and Business Media LLC. - 1572-8838 .- 0021-891X. ; 44:8, s. 917-926
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Tidskriftsartikel (refereegranskat)abstract
- While many attempts have been made in the recent past to improve the power conversion efficiencies of dye-sensitized solar cells (DSSCs), only a few reports can be found on the study of these cells using binary iodides in the gel polymer electrolyte. This paper reports the effect of using a binary mixture of (large and small cation) alkaline salts, in particular CsI and LiI, on the efficiency enhancement in DSSCs with gel polymer electrolytes. The electrolyte with the binary mixture of CsI:LiI = 1:1 (by weight) shows the highest ionic conductivity 2.9 x 10(-3) S cm(-1) at 25 A degrees C. DC polarization measurements showed predominantly ionic behavior of the electrolyte. The density of charge carriers and mobility of mobile ions were calculated using a newly developed method. The temperature dependent behavior of the conductivity can be understood as due to an increase of both the density and mobility of charge carriers. The solar cell with only CsI as the iodide salt gave an energy conversion efficiency of similar to 3.9 % while it was similar to 3.6 % for the cell with only LiI. However, the electrolyte containing LiI:CsI with mass ratio 1:1 showed the highest solar cell performance with an energy conversion efficiency of similar to 4.8 % under the irradiation of one Sun highlighting the influence of the mixed cation on the performance of the cell. This is an efficiency enhancement of 23 %.
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| 8. |
- Bandara, T M W J, 1968, et al.
(författare)
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Electrical and complex dielectric behaviour of composite polymer electrolyte based on PEO, alumina and tetrapropylammonium iodide
- 2017
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Ingår i: Ionics. - : Springer Science and Business Media LLC. - 0947-7047 .- 1862-0760. ; 23:7, s. 1711-1719
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the electrical, dielectric and morphological analysis of composite solid polymer electrolytes containing polyethylene oxide, alumina nano-fillers and tetrapropylammonium iodide are conducted. The temperature dependence of conductivity shows activation energy of 0.23, 0.20 and 0.29 eV for electrolytes containing 0, 5 and 15 wt.% alumina, respectively, when data fitted to the Arrhenius equation. These activation energy values are in good agreement with those determined from dielectric measurements. The result confirms the fact that conductivity is activated by both the mobility and the charge carrier density. The conductivity isotherms demonstrated the existence of two peaks, at 5 and 15 wt.% Al2O3 composition. The highest conductivity values of 2.4 × 10−4, 3.3 × 10−4 and 4.2 × 10−4 S cm−1 are obtained for the sample with 5 wt.% Al2O3 at 0, 12 and 24 °C, respectively, suggesting an enhancement of conductivity compared with that of alumina free samples.
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| 9. |
- Bandara, T M W J, 1968, et al.
(författare)
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High efficiency dye-sensitized solar cell based on a novel gel polymer electrolyte containing RbI and tetrahexylammonium iodide (Hex(4)NI) salts and multi-layered photoelectrodes of TiO2 nanoparticles
- 2019
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Ingår i: Renewable & Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 103, s. 282-290
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Tidskriftsartikel (refereegranskat)abstract
- High efficiency dye sensitized solar cells (DSSCs) have been achieved using a novel polymer gel electrolyte containing RbI and tetrahexylammonium iodide (Hex(4)NI) binary salts in combination with multi-layered TiO2 photoelectrodes. Performance enhancers were incorporated to the electrolyte to improve the efficiency in the DSSCs. Varying the salt mass fraction, showed that the conductivity in the electrolyte increases with increasing amount of RbI. The highest ionic conductivity of 4.19 mS cm(-1) is exhibited by the electrolyte sample with RbI: Hex(4)NI weight ratio of 3:1 at 25 degrees C. The temperature dependence of the electrolytes shows Arrhenius behavior. It is found that the electrolyte with RbI: Hex(4)NI weight ratio of 1.06:1 is more suitable for DSSC's applications and it has a conductivity of 3.77 mS cm(-1). A colloidal suspension of P25 TiO2 nanoparticles was used to make the spin coated photo-anodes in the form of stacks of 1-6 layers. The formation of a highly uniform and porous structure is observed with increasing number of layers from scanning electron microscopy and X-ray diffraction studies revealed that the layers are predominantly anatase phase with crystallite size of 19-22 nm. The band gap was estimated to be around 3.22 eV based on UV-Visible spectroscopy and found to be decreasing slightly with increasing layer thickness. The maximum efficiency of 7.5% and an impressively high current density of 20 mA cm(-2) were observed for the 4-layer device with the new gel electrolyte based on RbI and Hex(4)NI. This study not only brings reliability and consistency to the ways of preparing well-ordered TiO2 photoanodes but also offers the possibility of low-cost practical and highly efficient quasi-solid state DSSCs.
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| 10. |
- Bandara, T M W J, 1968, et al.
(författare)
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N719 and N3 dyes for quasi-solid state dye sensitized solar cells - A comparative study using polyacrylonitrile and CsI based electrolytes
- 2016
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Ingår i: Ceylon Journal of Science. - : Sri Lanka Journals Online (JOL). - 2513-230X .- 2513-2814. ; 45:2, s. 61-69
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Tidskriftsartikel (refereegranskat)abstract
- Dye sensitized solar cells offer a low cost alternative technology for solar energy harvesting. However, there are long term stability issues connected with these cells due to the liquid electrolytes normally used. Gel or solid polymer electrolytes which do not contain volatile solvents have been used in this investigation in order to alleviate these problems. Two types of solar cells were assembled using a double layered TiO2 film sensitized with two types of dye sensitizers, namely N719 (Ruthenizer 535-bisTBA) and N3 (Ruthenizer 535) in order to compare their performance. Quasi-solid-state electrolytes based on PAN (polyacrylonitrile) as the host polymer and CsI as the iodide salt were prepared by incorporating ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers. The conductivity of the electrolyte was further improved by adding tetrapropylammonium iodide (Pr4NI), 1-methyl 3-propyl imidazolium iodide (MPII) and 4-tert-butylpyridine (4TBP). The incorporation of these additives resulted in 17% enhancement in ionic conductivity. This improved electrolyte was used to fabricate the solar cells with N3 and N719 dyes. The efficiency of the N3 dye based solar cell was 3.85% whereas the efficiency of the N719 dye based solar cell was 4.14% representing a significant efficiency enhancement by 7.53% by the N719 dye. In addition, due to additives the solar cell efficiency has enhanced by 19% compared to the solar cell without any additive.
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| 11. |
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| 12. |
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| 13. |
- Halldin, S, et al.
(författare)
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Continuous long-term measurements of soil-plant-atmosphere variables at an agricultural site
- 1999
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Ingår i: AGRICULTURAL AND FOREST METEOROLOGY. - : ELSEVIER SCIENCE BV. - 0168-1923. ; 98-9, s. 75-102
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Tidskriftsartikel (refereegranskat)abstract
- It is a major challenge in modem science to decrease the uncertainty in predictions of global climate change. One of the largest uncertainties in present-day global climate models resides with the understanding of processes in the soil-vegetation-atmosphe
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Amaraweera, T. H. N. G., et al.
(författare)
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Surface modification of natural vein graphite for the anode application in Li-ion rechargeable batteries
- 2018
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Ingår i: Ionics. - : Springer Science and Business Media LLC. - 0947-7047 .- 1862-0760. ; 24:11, s. 3423-3429
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Tidskriftsartikel (refereegranskat)abstract
- Natural vein graphite with high purity and crystallinity is seldom used as anode material in lithium-ion rechargeable batteries (LIB) due to impurities and inherent surface structure. This study focuses on improving the surface properties of purified natural vein graphite surface by employing mild chemical oxidation. Needle-platy graphite sample with initial average carbon percentage of 99.83% was improved to 99.98% after treatment with 5 vol.% HCl. Surface modification of purified graphite was done by chemical oxidation with (NH4)(2)S2O8 and HNO3. Fourier-transform infrared spectra of graphite after chemical indicating surface oxidation of graphite surface. X-ray diffraction and scanning electron microscopic studies show the improvement of graphite structure without modification of crystalline structure. Electrochemical performance of lithium-ion cell assembled with developed anode material shows noticeable improvement of the reversible capacity and coulombic efficiency in the first cycle and cycling behavior after surface modification.
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| 18. |
- Bandara, T M W J, 1968, et al.
(författare)
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A polymer electrolyte containing ionic liquid for possible applications in photoelectrochemical solar cells
- 2010
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1432-8488 .- 1433-0768. ; 14:7, s. 1221-1226
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Tidskriftsartikel (refereegranskat)abstract
- Various iodide ion conducting polymer electrolytes have been studied as candidate materials for fabricating photoelectrochemical (PEC) solar cells and energy storage devices. In this study, enhanced ionic conductivity values were obtained for the ionic liquid tetrahexylammonium iodide containing polyethylene oxide (PEO)-based plasticized electrolytes. The analysis of thermal properties revealed the existence of two phases in the electrolyte, and the conductivity measurements showed a marked conductivity enhancement during the melting of the plasticizer-rich phase of the electrolyte. Annealed electrolyte samples showed better conductivity than nonannealed samples, revealing the existence of hysteresis. The optimum conductivity was shown for the electrolytes with PEO:salt= 100:15 mass ratio, and this sample exhibited the minimum glass transition temperature of 72.2 °C. For this optimum PEO to salt ratio, the conductivity of nonannealed electrolyte was 4.4×10−4 S cm−1 and that of the annealed sample was 4.6×10−4 S cm−1 at 30 °C. An all solid PEC solar cell was fabricated using this annealed electrolyte. The short circuit current density (ISC), the open circuit voltage (VOC), and the power conversion efficiency of the cell are 0.63 mA cm−2, 0.76 V, and 0.47% under the irradiation of 600 W m−2 light.
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| 19. |
- Bandara, T M W J, 1968, et al.
(författare)
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Dependence of solar cell performance on the nature of alkaline counterion in gel polymer electrolytes containing binary iodides
- 2017
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1432-8488 .- 1433-0768. ; 21:6, s. 1571-1578
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Tidskriftsartikel (refereegranskat)abstract
- Performance of dye-sensitized nano-crystalline TiO2 thin film-based photo-electrochemical solar cells (PECSCs) containing gel polymer electrolytes is largely governed by the nature of the cation in the electrolyte. Dependence of the photovoltaic performance in these quasi-solid state PECSCs on the alkaline cation size has already been investigated for single cation iodide salt-based electrolytes. The present study reports the ionic conductivity dependence on the nature of alkaline cations (counterion) in a gel polymer electrolyte based on binary iodides. Polyacrylonitrile-based gel polymer electrolyte series containing binary iodide salts is prepared using one of the alkaline iodides (LiI, NaI, KI, RbI, and CsI) and tetrapropylammonium iodide (Pr4NI). All the electrolytes based on binary salts have shown conductivity enhancement compared to their single cation counterparts. When combined with Pr4NI, each of the Li+, Na+, K+, Rb+, and Cs+ cation containing iodide salts incorporated in the gel electrolytes has shown a room temperature conductivity enhancement of 85.59, 12.03, 12.71, 20.77, and 15.36%, respectively. The conductivities of gel electrolytes containing binary iodide systems with Pr4NI and KI/RbI/CsI are higher and have shown values of 3.28, 3.43, and 3.23 mS cm(-1), respectively at room temperature. The influence of the nature of counterions on the performance of quasi-solid state dye-sensitized solar cells is investigated by assembling two series of cells. All the binary cationic solar cells have shown more or less enhancements of open circuit voltage, short circuit current density, fill factor, and efficiency compared to their single cation counterparts. This work highlights the importance of employing binary cations (a large and a small) in electrolytes intended for quasi-solid state solar cells. The percentage of energy conversion efficiency enhancement shown for the PECSCs made with electrolytes containing Pr4NI along with Li+, Na+, K+, Rb+, and Cs+ iodides is 260.27, 133.65, 65.27, 25.32, and 8.36%, respectively. The highest efficiency of 4.93% is shown by the solar cell containing KI and Pr4NI. However, the highest enhancements of ionic conductivity as well as the energy conversion efficiency were exhibited by the PECSC made with Li+-containing binary cationic electrolyte.
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| 20. |
- Bandara, T M W J, 1968, et al.
(författare)
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Dye-sensitized, nano-porous TiO2 solar cell with poly(acrylonitrile): MgI2 plasticized electrolyte
- 2010
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 195:11, s. 3730-3734
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Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized solar cells are promising candidates as supplementary power sources; the dominance in the photovoltaic field of inorganic solid-state junction devices is in fact now being challenged by the third generation of solar cells based on dye-sensitized, nano-porous photo-electrodes and polymer electrolytes. Polymer electrolytes are actually very favorable for photo-electrochemical solar cells and in this study poly(acrylonitrile)–MgI2 based complexes are used. As ambient temperature conductivity of poly(acrylonitrile)–salt complexes are in general low, a conductivity enhancement is attained by blending with the plasticizers ethylene carbonate and propylene carbonate. At 20 °C the optimum ionic conductivity of 1.9 × 10−3 S cm−1 is obtained for the (PAN)10(MgI2)n(I2)n/10(EC)20(PC)20 electrolyte where n = 1.5. The predominantly ionic nature of the electrolyte is seen from the DC polarization data. Differential scanning calorimetric thermograms of electrolyte samples with different MgI2 concentrations were studied and glass transition temperatures were determined. Further, in this study, a dye-sensitized solar cell structure was fabricated with the configuration Glass/FTO/TiO2/Dye/Electrolyte/Pt/FTO/Glass and an overall energy conversion efficiency of 2.5% was achieved under solar irradiation of 600 W m−2. The I–V characteristics curves revealed that the short-circuit current, open-circuit voltage and fill factor of the cell are 3.87 mA, 659 mV and 59.0%, respectively.
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| 21. |
- Bandara, T M W J, 1968, et al.
(författare)
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Effect of cation size on the performance of dye sensitized nanocrystalline TiO2 solar cells based on quasi-solid state PAN electrolytes containing quaternary ammonium iodides
- 2013
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 109, s. 609-616
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Tidskriftsartikel (refereegranskat)abstract
- The performance of dye sensitized nanocrystalline TiO2 solar cells based on quasi-solid state PAN electrolytes containing a series of six quaternary ammonium iodide salts NH4I, Eth(4)NI, Prop(4)NI, But(4)NI, Pent(4)NI, Hex(4)NI with different cation sizes has been evaluated. Even though the total ionic conductivity decreases with increasing cation size from NH4I to Hex(4)NI, the iodide ion conductivity in the electrolytes increases with cation size. The open circuit photovoltage (V-oc) of the dye sensitized solar cells also increases with cation radius. The efficiency of the DSSCs varies with cation size and exhibits a maximum for Prop(4)NI salt. The short circuit photo current density (J(sc)) follows a similar variation with cation size, suggesting a strong correlation between the cation size dependence of efficiency and J(sc). The DSSC fabricated with tetrapropylammonium iodide exhibited the maximum efficiency of 4.30% with maximum J(sc) of 10.78 mA cm(-2) and a V-oc of 0.746 V. The results have been interpreted on the basis of "the electrolyte effects" where J(sc) is determined essentially by the iodide ion conductivity and "the electrode effects" where the J(sc) and V-oc are determined by the cation adsorption in the dyed TiO2 electrode and resulting electron dynamics at the semiconductor/electrolyte interface. For DSSCs with small cations, electrolyte effects appear to be dominating and rate determining while for DSSCs with larger cations, electrode effects appear to be dominating and rate determining. (C) 2013 Elsevier Ltd. All rights reserved.
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| 22. |
- Bandara, T M W J, 1968, et al.
(författare)
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Effect of the alkaline cation size on the conductivity in gel polymer electrolytes and their influence on photo electrochemical solar cells
- 2016
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 18:16, s. 10873-10881
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Tidskriftsartikel (refereegranskat)abstract
- The nature and concentration of cationic species in the electrolyte exert a profound influence on the efficiency of nanocrystalline dye-sensitized solar cells (DSSCs). A series of DSSCs based on gel electrolytes containing five alkali iodide salts (LiI, NaI, KI, RbI and CsI) and polyacrylonitrile with plasticizers were fabricated and studied, in order to investigate the dependence of solar cell performance on the cation size. The ionic conductivity of electrolytes with relatively large cations, K+, Rb+ and Cs+, was higher and essentially constant, while for the electrolytes containing the two smaller cations, Na+ and Li+, the conductivity values were lower. The temperature dependence of conductivity in this series appears to follow the Vogel-Tamman-Fulcher equation. The sample containing the smallest cation shows the lowest conductivity and the highest activation energy of similar to 36.5 meV, while K+, Rb+ and Cs+ containing samples show an activation energy of similar to 30.5 meV. DSSCs based on the gel electrolyte and a TiO2 double layer with the N719 dye exhibited an enhancement in the open circuit voltage with increasing cation size. This can be attributed to the decrease in the recombination rate of electrons and to the conduction band shift resulting from cation adsorption by TiO2. The maximum efficiency value, 3.48%, was obtained for the CsI containing cell. The efficiencies shown in this study are lower compared to values reported in the literature, and this can be attributed to the use of a single salt and the absence of other additives, since the focus of the present study was to analyze the cation effect. The highest short circuit current density of 9.43 mA cm(-2) was shown by the RbI containing cell. The enhancement of the solar cell performance with increasing size of the cation is discussed in terms of the effect of the cations on the TiO2 anode and ion transport in the electrolyte. In liquid electrolyte based DSSCs, the short circuit current density has been reported to decrease with the increasing size of the cation. However, in this work, it follows an opposite trend highlighting a major difference between liquid and quasi-solid electrolytes on the solar cell performance.
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| 23. |
- Bandara, T M W J, 1968, et al.
(författare)
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Effect of thermal history and characterization of plasticized, composite polymer electrolyte based on PEO and tetrapropylammonium iodide salt (Pr4N+I-).
- 2009
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 180:4-5, s. 362-
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Tidskriftsartikel (refereegranskat)abstract
- The search for anionic conductors based on solid polymer electrolytes is important for the development of photo-electrochemical (PEC) solar cells due to their many favourable chemical and physical properties. Although solid polymer electrolytes have been extensively studied as cation, mainly lithium ion, conductors for applications in secondary batteries, their use as anionic conductors have not been studied in greater detail. In a previous paper we reported the application of a PEO based iodide ion conducting electrolyte in a PEC solar cell. This electrolyte had the composition PEO: Pr4N+I- = 9:1 with 50 wt.% ethylene carbonate (EC). In this work we have studied the effect of incorporating alumina filler on the properties of this electrolyte. The investigation was extended to electrical and dielectric measurements including high frequency impedance spectroscopy and thermal analysis.In the DSC themograms two endothermic peaks have been observed on heating, one of these peaks is attributed with the melting of the PEO crystallites, while the other peak with a melting temperature similar to 30 degrees C is attributed to the melting of the EC rich phase. The melting temperature of both these peaks shows a marked variation with alumina content in the electrolyte. The temperature dependence of the conductivity shows that there is an abrupt conductivity increase in the first heating run evidently due to the melting of the EC rich phase. High conductivity values are retained at lower temperatures in the second heating. Conductivity isotherms show the existence of two maxima, one at -5% Al2O3 content and the other at similar to 15%. The occurrence of these two maxima has been explained in terms of the interactions caused by alumina grains, the crystallinity and melting of the PEO rich phase. As seen from latent heat of melting, the crystallinity of the electrolyte has reduced considerably during the first heating run. In contrast to the conductivity enhancement caused by ceramic fillers in PEO-based cation containing electrolytes, no conductivity enhancement has been observed in the present PEO based anionic conducting materials by adding alumina except at low temperatures. (C) 2009 Elsevier B.V. All rights reserved.
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| 24. |
- Bandara, T M W J, 1968, et al.
(författare)
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Efficiency of 10 % for quasi-solid state dye-sensitized solar cells under low light irradiance
- 2015
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Ingår i: Journal of Applied Electrochemistry. - : Springer Science and Business Media LLC. - 0021-891X .- 1572-8838. ; 45:4, s. 289-298
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Tidskriftsartikel (refereegranskat)abstract
- Polyacrylonitrile-based gel electrolytes were prepared using tetrapropylammonium iodide salt for dye-sensitized solar cells (DSSCs). The optimized gel electrolyte exhibited an ionic conductivity of 2.6 mS cm(-1) at 25 A degrees C and the DSSC fabricated with this gel electrolyte showed open-circuit voltage, short-circuit current density, fill factor, and efficiency of 0.71 V, 11.8 mA, 51, and 4.2 %, respectively, under one sun irradiation. The efficiency of the cell increases increased with decreasing solar irradiance achieving 10 % efficiency and 80 % fill factor at 3 mW cm(-2) a low irradiance value of 3 mW cm(-2). Lower efficiencies at higher intensities were attributed to transport limitation of the redox mediators at high irradiation intensities. This work suggests that quasi-solid state DSSCs can reach efficiencies close to that of liquid electrolyte-based cells at low irradiance levels. The results open up new vistas on efficiency improvement in DSSCs by optical manipulation and control of DSSCs.
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| 25. |
- Bandara, T M W J, 1968, et al.
(författare)
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Performance enhancers for gel polymer electrolytes based on LiI and RbI for quasi-solid-state dye sensitized solar cells
- 2016
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:105, s. 103683-103691
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, the effect of additives (enhancers) on efficiency enhancement in dye sensitized solar cells (DSSCs) containing two series of gel polymer electrolytes, one based on LiI and the other based on RbI have been systematically studied. Polyacrylonitrile (PAN) was used as the host polymer while the performance enhancers used in each case were tetrapropylammoniumiodide (Pr4NI), the ionic liquid 1-methyl-3-propyl imidazolium iodide (MPII) and 4-tert-butylpyridine (4TBP) respectively. Appropriate amounts of the selected enhancers were incorporated one by one, in LiI based and RbI based gel electrolytes. The incorporation of Pr4NI and MPII led to an increase in conductivity of the electrolyte, while 4TBP showed a decrease in conductivity. The maximum conductivity of 3.85 mS cm(-1) at room temperature was shown by the RbI based-series while for the LiI based series the maximum conductivity was 2.95 mS cm(-1). Each of these electrolytes with respective additives was used to fabricate quasi-solid state DSSCs. For the DSSCs based on the LiI containing series, a significant short circuit current density (J(sc)) enhancement (161%) from 3.65 to 9.54 mA cm(-2) was observed due to the addition of Pr4NI. This J(sc) value further increased to 9.7 mA cm(-2) due to the addition of MPII and 4TBP. For the DSSCs with corresponding Rb based electrolytes with all three additives, the highest J(sc) value obtained was 11.5 mA cm(-2). The incorporation of the three additives Pr4NI, MPII and 4TBP collectively enhanced the open circuit voltages and the efficiencies of both LiI and RbI containing quasi-solid state DSSCs. Another important finding from this work is that rarely used RbI containing electrolytes exhibit superior DSSC performance compared to more frequently used LiI based electrolytes. Hence, RbI appears to be a better candidate compared to LiI to fabricate gel polymer electrolytes for DSSCs in general. The three additives have contributed to a remarkable efficiency enchantment in DSSCs by 449.3% for the LiI based electrolyte and by 35.7% for the RbI based electrolyte.
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| 26. |
- Bandara, T M W J, 1968, et al.
(författare)
-
Tetrahexylammonium iodide containing solid and gel polymer electrolytes for dye sensitized solar cells
- 2012
-
Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 14, s. 1607-1612
-
Konferensbidrag (refereegranskat)abstract
- The performance evaluation plays a more and more important role in the modern enterprise management, and the method of evaluation system on enterprise performance is always an important question in the theory and practice. So this paper set up a scientific, reasonable performance evaluation index system which was especially suitable for the small and medium third party logistics enterprise from the four levels of financial, customers, business and innovation. Meanwhile, according to the index system, it gave a performance evaluation with the Chinese access logistics corporation. The results showed that the construction of the index system was reasonable, and the evaluation results also were reliable.
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| 27. |
- Bandara, T M W J, 1968, et al.
(författare)
-
Thermal and dielectric properties of PEO/EC/Pr4N+I- polymer electrolytes for possible applications in photo-electro chemical solar cells.
- 2009
-
Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1432-8488 .- 1433-0768. ; 13:8
-
Tidskriftsartikel (refereegranskat)abstract
- The anion-conducting polymer electrolyte polyethylene oxide (PEO)/ethylene carbonate (EC)/Pr4N+I-/I-2 is a candidate material for fabricating photo-electrochemical (PEC) solar cells. Relatively high ionic conductivity values are obtained for the plasticized electrolytes; at room temperature, the conductivity increases from 7.6 x 10(-9) to 9.5 x 10(-5) S cm(-1) when the amount of EC plasticizer increases from 0% to 50% by weight. An abrupt conductivity enhancement occurs at the melting of the polymer; above the melting temperature, the conductivity can reach values of the order of 10(-3) S cm(-1). The melting temperature decreases from 66.1 to 45.1 A degrees C when the EC mass fraction is increased from 0% to 50%, and there is a corresponding reduction in the glass transition temperature from -57.6 to -70.9 A degrees C with the incorporation of the plasticizer. The static dielectric constant values, epsilon(s), increase with the mass fraction of plasticizer, from 3.3 for the unplasticized sample to 17.5 for the 50% EC sample. The dielectric results show only small traces of ion-pair relaxations, indicating that the amount of ion association is low. Thus, the iodide ion is well dissociated, and despite its large size and relatively low concentration in these samples, the iodide ion to ether oxygen ratio is 1:68, a relatively efficient charge carrier. A further enhancement of the ionic conductivity, especially at lower temperatures, is however desired for these applications.
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| 28. |
- Bandara, T M W J, 1968, et al.
(författare)
-
Transport parameters of charge carriers in PEO-LiTf-based, plasticized, composite, and plasticized-composite electrolytes intended for Li-ion batteries
- 2022
-
Ingår i: Ionics. - : Springer Science and Business Media LLC. - 0947-7047 .- 1862-0760. ; 28:6, s. 2701-2714
-
Tidskriftsartikel (refereegranskat)abstract
- Solid polymer electrolytes are a key component in many electrochemical devices such as dye-sensitized solar cells, batteries, and supercapacitors. In this study, three electrolytes based on polyethylene oxide (PEO) host polymer, ethylene carbonate (EC) plasticizer, and Al2O3 filler were investigated. The polymer electrolytes (PEO)9(EC)9(LiCF3SO3)2, (PEO)9(LiCF3SO3)2(Al2O3)0.75, and (PEO)9(EC)9(LiCF3SO3)2(Al2O3)0.75 were characterized by analyzing DC conductivity, the frequency dependence of AC conductivity, and complex dielectric function. The conductivities of the plasticized, composite, and plasticized-composite electrolytes at 26 °C increase from 6.25, 0.009, and 2.96 mS cm-1 to 21.5, 0.12, and 11.4 mS cm-1, respectively, when the temperature increased to 70 °C. For the in-depth analysis of electrolytes, dielectric analysis was used to determine the charge carrier density (n), mobility (μ), and diffusion coefficient (D) using a newly developed method. Further, the investigation extended to study the temperature dependence of n, D, and μ. The study reveals that EC can increase the ionic conductivity by increasing n, and conversely, filler contributes by increasing μ, respectively. At 26 °C, (PEO)9(EC)9(LiCF3SO3)2(Al2O3)0.75 shows D, μ, and n of 3.8×10-11 m2 s-1, 1.5×10-9 m2 V-1 s-1, and 1.3×1027 m-3, respectively. The values obtained for D, μ, and n parameters of the plasticized electrolytes agree with those available for similar electrolytes, while the composite electrolyte showed considerably lower values for n. The complex impedance analysis can be used to determine transport parameters of all the types (plasticized, composite, and plasticized composite) of polymer electrolytes.
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| 29. |
- Bokalawela, R., 0, et al.
(författare)
-
H-2/Pt/Ce0.9Gd0.1O1.95/Pt/O-2 fuel cell operated in the intermediate temperature range 500-700 degrees C
- 2004
-
Ingår i: IONICS. - 0947-7047 .- 1862-0760. ; 10:1-2, s. 84-87
-
Konferensbidrag (refereegranskat)abstract
- Ce0.9Gd0.1O1.95 (GCO), is one of the potential candidate electrolytes for intermediate temperature Solid Oxide Fuel Cells (ITSOFC). GCO has high oxide ion conductivity in the intermediate temperature range (500 - 700 degrees C) compared to other C1-yGdyO2-2/y compositions and the Gd3+ ion is the most appropriate dopant material compared to other rare earth materials such as Sm3+, Y3+, Zr3+, etc. Our results show that the fuel cell H-2/Pt/Ce0.9Gd0.1O1.95/O-2 operated in the temperature range 500 - 700 degrees C gives the maximum power densities 0.0049 W/cm(2) at 500 degrees C and 0.0126 W/cm(2) at 650 degrees C for cell voltages 0.6275 V and 0.6278 V, respectively, where the electrolyte was kept in 5% H-2(+ Argon) for 12 hours before use in the fuel cell. Maximum power densities are 0.0038 W/cm(2) at 500 degrees C and 0.0270 W/cm(2) at 650 degrees C for cell voltages 0.5986 and 0.5913 V, respectively, where the electrolyte was kept in 2 % O-2(+ Argon) for 12 hours before use in the fuel cell.
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| 30. |
- Buraidah, M. H., et al.
(författare)
-
High efficient dye sensitized solar cells using phthaloylchitosan based gel polymer electrolytes
- 2017
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 245, s. 846-853
-
Tidskriftsartikel (refereegranskat)abstract
- High efficiency of 9.61% has been produced for dye sensitized solar cell using a phthaloylchitosan based gel polymer electrolyte. The gel polymer electrolytes have been optimized by varying the amount of tetrapropylammonium iodide (TPAI) and 1-butyl-3-methylimidazolium iodide (BMII) ionic liquid (IL). The highest ionic conductivity of gel polymer electrolyte containing 8 wt.% IL was obtained with the value of 13.5 mS cm(-1). The temperature dependence ionic conductivity follows Arrhenius rule. The highest conducting electrolyte also exhibits the highest diffusion coefficient of triiodide ion which is 3.9 X 10(-7) cm(-2) s(-1). The optimized gel polymer electrolyte exhibits the highest short circuit current density of 19.68 mA cm(-2).
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| 31. |
- Buraidah, M. H., et al.
(författare)
-
Solar Module Using Dye-Sensitized Solar Cells
- 2018
-
Ingår i: International Conference on Transparent Optical Networks. - 2162-7339. ; 2018-July
-
Konferensbidrag (refereegranskat)abstract
- Solar module in this work comprises dye sensitized solar cells (DSSC) in series connection. The DSSC is made from transparent fluorine-doped tin oxide (FTO) glass on which two layers of titanium dioxide (TiO2) have been deposited and then soaked in ruthenium dye to form the photoanode. A phthaloylchitosan based gel polymer electrolyte containing iodide/triiodide redox mediator was sandwiched between the photoanode and platinum counter electrode. The two layers of TiO2 have different particle sizes. The first layer ( 15 nm particle size) acts as blocking layer whereas the second layer (particle size 21 nm) is mesoporous. The current-voltage characteristics and impedance measurements have been performed on the solar panel. Results show that the solar module comprising five DSSCs connected in series is capable to produce current around 0.7 mA•cm-2, voltage of 3.3 V and power density of 1.1 mW•cm-2 under solar simulator with light intensity of 18 mW•cm-2. The feasibility of the solar panel has been tested in practical applications e.g. operating small decorative items that require small power to function.
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| 32. |
- Correa, Miquel
(författare)
-
On new homes and green lands : Three microeconometric essays as if urban costs and rural sustainability mattered
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is structured as a compendium of three self-contained articles, all single-authored. In the first paper, I analyze the effect of a mortgage cap, a policy implemented as a macroeconomic prudential measure by the Swedish Financial Supervisory Authority in 2010, on the likelihood of the young adult population purchasing a house in Sweden. I find that the purchasing rate decreases less for the wealth-constrained individuals in relation to the wealth-unconstrained during a four-year period after the implementation of the policy.In the second paper, I examine how experiencing working from home (WFH) during the COVID-19 pandemic contributed to out-migration of the working-age population of large Swedish cities. Using register microdata of individuals in the period 2015–2021, the results show that the remote work experiment significantly increased the likelihood of moving out of large cities and of moving to the hinterlands compared to the usual internal migration flows before the pandemic.Finally, I analyze the role of geographical and cognitive proximity in the decision to adopt organic farming in Sweden for the period 2010–2016. I find that the nearby presence of earlier adopters in a parish influences current adoption, indicating the existence of proximity effects in the diffusion of environmentally sustainable technologies across a diversity of farming industries in Sweden. The effect also becomes more pronounced when farmers share cognitive similarities, defined as per type of farming industry, in particular for the dairy sector and mixed farming activities.
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| 33. |
- Dissanayake, M. A. K. L., et al.
(författare)
-
A novel multilayered photoelectrode with nitrogen doped TiO2 for efficiency enhancement in dye sensitized solar cells
- 2017
-
Ingår i: Journal of Photochemistry and Photobiology A: Chemistry. - : Elsevier BV. - 1010-6030. ; 349, s. 63-72
-
Tidskriftsartikel (refereegranskat)abstract
- Nitrogen doped TiO2 powder samples were synthesized by a modified wet chemical method using aqueous ammonia and nitrogen gas purged on titanium tetra isopropoxide (TTIP). Photolectrodes with different combinations of layers of nitrogen − doped TiO2, undoped TiO2 and Degussa P25 TiO2 powders were used in dye sensitized solar cells (DSSCs). The highest conversion efficiency of 8.00% was achieved by the cells fabricated with compact layer/P25/N-doped TiO2 multilayer photoelectrode. This is an impressive enhancement in efficiency close to 89% with respect to a similar multilayer electrode made with undoped TiO2 which showed a conversion efficiency of 4.22%. The enhancement in the efficiency appears to be due to the increased photocurrent density of the DSSCs resulting mainly from energy band gap narrowing due to N-doping with some contribution from increased dye uptake by the novel multilayer electrode. These results have been substantiated by the reduced charge transfer resistance obtained from Electrochemical Impedance Spectra and the enhanced IPCE spectra of the DSSCs with N-doped TiO2 based multilayer electrode. © 2017 Elsevier B.V.
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| 34. |
- Dissanayake, M. A K L, et al.
(författare)
-
Effect of concentration and grain size of alumina filler on the ionic conductivity enhancement of the (PEO)9LiCF3SO3:Al2O3 composite polymer electrolyte
- 2003
-
Ingår i: Journal of Power Sources. - 0378-7753.
-
Konferensbidrag (refereegranskat)abstract
- Nano-composite polymer electrolytes are receiving attention as potential candidates to be used as electrolyte membranes in lithium polymer batteries and other devices. However, a survey of literature reveals that a systematic study of the effect of concentration and surface area of ceramic fillers on the conductivity enhancement of micro- and nano-composite polymer electrolytes is lacking. In this work, we have studied the thermal and electrical properties of the composite polymer electrolyte (PEO)9LiCF3SO3 + Al2O3 incorporating alumina filler grains of four different sizes with different specific surface areas. The results show that the PEO crystallite melting temperature decreased by a few degrees in samples with fillers exhibiting a minimum for samples with high conductivity. The presence of the filler enhanced the ionic conductivity substantially above as well as below 60 °C, and the nano-porous alumina grains with 5.8 nm pore size and 150 m2/g specific area and 15 wt.% filler concentration exhibited the maximum enhancement. The observed conductivity enhancement has been attributed to Lewis acid-base type surface interactions of ionic species with O/OH groups on the filler surface, with an additional contribution below 60 °C coming from the retention of an increased fraction of the amorphous phase due to the presence of the filler. The conductivity versus filler concentration curves exhibit two conductivity maxima which has been explained in terms of the surface interactions, blocking effect and grain consolidation. The conductivity enhancement appears to saturate beyond 100 m2/g grain surface area. © 2003 Elsevier Science B.V. All rights reserved.
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| 35. |
- Dissanayake, M.A.K.L., et al.
(författare)
-
Efficiency enhancement by mixed cation effect in dye-sensitized solar cells with PAN based gel polymer electrolyte
- 2012
-
Ingår i: Journal of Photochemistry and Photobiology A: Chemistry. - : Elsevier BV. - 1010-6030. ; 246, s. 29-35
-
Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized solar cells based on nano-porous TiO2 photo-anode and quasi-solid polymer (or gel) electrolytes are emerging as low cost alternatives to conventional inorganic photovoltaic devices. Although many attempts have been made in order to improve the relatively low power conversion efficiencies of these solar cells, to our knowledge there are very few reports aimed at using a binary system of two different iodide salts toward efficiency enhancement in these cells. In this paper we report for the first time in detail, the effect of using a binary iodide salt mixture with different size cations on the efficiency enhancement in dye sensitized solar cells with polyacrylonitrile (PAN) based gel polymer electrolyte and suggest a possible mechanism for this enhancement, based on short circuit photocurrent which is directly related to the iodide ion concentration [I-]. The gel electrolyte was made of PAN, ethelene carbonate (EC), Propylene carbonate (PC), salt mixture and I-2. The binary iodide salt mixture consists of potassium iodide (KI) and Tetra propyl ammonium iodide (Pr4NI). Although the gel electrolyte with 100% (w/w) KI exhibited the highest overall ionic conductivity at room temperature, it showed the lowest iodide ion (I-) contribution to conductivity. On the other hand, the electrolyte with 100% (w/w) Pr4NI exhibited the lowest overall ionic conductivity but had the highest iodide ion(I-) contribution. The dye-sensitized solar cells of configuration Glass/FTO/TiO2/N-719 Dye/electrolyte/Pt/FTO/glass were fabricated using the gel electrolytes of different salt ratios and with nanoporous TiO2 electrode sensitized with Ruthenium dye (N719). With identical electrolyte compositions, the solar cell with 100% (w/w) KI showed an efficiency of 4.98% and the cell with 100% (w/w) Pr4NI showed an efficiency of 4.47%. However, the cell with the mixed iodide system, 16.6% (w/w) KI + 83.4%(w/w) Pr4NI showed the highest efficiency of 5.36% with maximum short circuit current density (J(SC)) of 13.79 mA cm(-2), open circuit voltage (V-OC) of 679.10 mV and a fill factor of 57.25%. The variation of efficiency (eta) with iodide ion concentration [I-] follows the same trend as the J(SC) which appears to be governed by the iodide ion conductivity of the gel electrolyte. The dependence of the short circuit photocurrent and the open circuit photovoltage on the cation type generally agrees with reported data for related systems. However, the occurrence of a maximum in the solar cell efficiency and short circuit photocurrent at 16.6% (w/w)10 + 83.4% (w/w) Pr4NI salt composition is an important finding. The efficiency enhancement of about 8% achieved by employing the binary iodide mixture in the gel electrolyte instead of a single iodide salt, could be utilized for achieving efficiency enhancement in many dye sensitized solar cell systems based on polymeric, gel or solvent electrolytes.
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| 36. |
- Dissanayake, M. A. K. L., et al.
(författare)
-
High-efficiency dye-sensitized solar cells fabricated with electrospun PVdF-HFP polymer nanofibre-based gel electrolytes
- 2023
-
Ingår i: Bulletin of Materials Science. - 0973-7669 .- 0250-4707. ; 46:2
-
Tidskriftsartikel (refereegranskat)abstract
- Poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) electrospun polymer nanofibre-based quasi-solid or gel electrolytes were successfully fabricated by incorporating a liquid electrolyte within the nanofibre membrane. The dye-sensitized solar cells (DSSCs) fabricated with gel and with liquid electrolyte were characterized by photocurrent–voltage measurements and electrochemical impedance spectroscopy measurements. The maximum efficiency (η) of 6.79% was observed for the DSSC fabricated with optimized nanofibre membrane thickness, corresponding to 4 min of electrospinning time. The optimized PVdF-HFP nanofibre gel electrolyte shows an ionic conductivity of 7.16 × 10−3 S cm–1 at 25°C, while the corresponding liquid electrolyte exhibits an ionic conductivity of 11.69 × 10–3 S cm–1 at the same temperature. The open circuit voltage (Voc), short circuit current density (Jsc) and fill factor were recorded as 801.40 mV, 12.70 mA cm–2, and 66.67%, respectively, at an incident light intensity of 100 mW cm–2 with a 1.5 AM filter. The nanofibre gel electrolyte-based cell showed an efficiency of 6.79%, whereas the efficiency of the conventional liquid electrolyte-based cell was 7.28% under the same conditions. Furthermore, nanofibre gel electrolyte-based cells exhibited better stability, maintaining 85.40% of initial efficiency after 120 h. These results show that the optimized, polymer nanofibre-based gel electrolyte can be used successfully to replace the liquid electrolyte in DSSCs without much loss of efficiency but improving the stability while minimizing most of the drawbacks associated with liquid electrolytes.
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| 37. |
- Dissanayake, M. A. K. L., et al.
(författare)
-
Highly efficient, PbS:Hg quantum dot-sensitized, plasmonic solar cells with TiO2 triple-layer photoanode
- 2019
-
Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1433-0768 .- 1432-8488. ; 23:6, s. 1787-1794
-
Tidskriftsartikel (refereegranskat)abstract
- Highly efficient, PbS:Hg quantum dot-sensitized, plasmonic solar cells with TiO2 triple-layer photoanode were fabricated by successive ionic layer adsorption and reaction (SILAR) method. These nanostructured photoanodes were characterized by optical and morphological techniques and the solar cells were characterized by optical and electrical techniques. The light absorption by the photoanode was enhanced by effective light scattering process using a triple-layer TiO2 nanostructure, fabricated with a TiO2 nanofiber layer sandwiched between two TiO2 nanoparticle layers. The best plasmon-enhanced quantum dot-sensitized solar cell showed an efficiency of 5.41% with short circuit current density of 18.02mAcm(-2) and open-circuit voltage of 679.83mV. The overall efficiency and photocurrent density of the Q-dot-sensitized solar cell are enhanced by 15.84% and 38.83% respectively due to the plasmonic effect. The enhanced efficiency appears to be due to the improved short circuit current density by increased light absorption by the triple-layered photoanode nanostructure as well as by the localized surface plasmon resonance (LSPR) effect of the plasmonic gold nanoparticles. This is the first report on plasmon-enhanced, triple-layered TiO2 photoanode sensitized with PbS:Hg Q-dots.
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| 38. |
- Dissanayake, M.A.K.L., et al.
(författare)
-
Polymethylmethacrylate (PMMA) based quasi-solid electrolyte with binary iodide salt for efficiency enhancement in TiO2 based dye sensitized solar cells
- 2014
-
Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 264, s. 85-91
-
Tidskriftsartikel (refereegranskat)abstract
- Enhancement of efficiency by using iodide mixture (Pr4NI and I(1), instead of a single iodide salt, in N719 dye-sensitized solar cells with a polymethylmethacrylate (PMMA) based gel electrolyte is investigated. The salt ratio is varied to optimize efficiency. With 100 wt.% KI and 100 wt.% (Pr4NI) efficiencies under AM 1.5 illumination are 3.39% and 3.21%, while 22.2:77.8 wt.% ratio KI:Pr4NI shows the highest efficiency of 3.99%. This is an efficiency enhancement of 18%. Variation of efficiency with salt composition appears to correspond to the change in short circuit photocurrent density (J(sc)) and the iodide ion conductivity.
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| 39. |
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| 40. |
- Florida, Richard L., et al.
(författare)
-
The city as startup machine : The urban underpinnings of modern entrepreneurship
- 2020
-
Ingår i: Urban Studies and Entrepreneurship. - Cham : Springer. - 9783030151645 - 9783030151638 ; , s. 19-30
-
Bokkapitel (refereegranskat)abstract
- This chapter lays out the connection between urbanism and entrepreneurship. For decades, it was thought that startup activity tended to cluster in suburban office parks or “nerdistans” like those of California’s Silicon Valley. We argue that tech startups are increasingly clustered in large global cities and metro areas and in denser urban neighborhoods or districts within those cities. In effect, the city stands as the organizing unit platform for entrepreneurial activity, bringing together the talent, knowledge, capital, and other assets required for it to occur. To advance this argument, the chapter marries the literatures on entrepreneurship going back to the seminal contributions of Joseph Schumpeter to the theories of urban clustering and dynamic cities associated with Jane Jacobs, Alfred Marshall, and their disciples. It then arrays a variety of empirical evidence on the location of high-tech startup activity to make this case, including data on the concentration of venture capital investment in high-tech startups in large global cities and in dense urban neighborhoods within those large cities. It also discusses the rise of a new segment of high-technology industry, urban tech, which spans new sectors like ride hailing, co-living, co-working, real estate technology, construction technology, and smart city technology, which has made the city not just the platform for but the object of entrepreneurial startup activity.
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| 41. |
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| 42. |
- Hahn-Zoric, M, et al.
(författare)
-
Variable increases of IgG and IgM antibodies in milk of IgA deficient women.
- 1997
-
Ingår i: Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology. - 0905-6157. ; 8:3, s. 127-33
-
Tidskriftsartikel (refereegranskat)abstract
- Serum, milk and saliva from seven IgA deficient mothers were studied for the presence of IgA, IgG and IgM antibodies to Escherichia coli and poliovirus antigens. Different variable patterns were obtained. One mother had very much increased IgM and IgG antibodies in milk and saliva against both antigens; the milk IgG antibodies were 11-14 times higher than the reference milk pool. Another mother showed also striking increases of both IgM and IgG antibodies in milk, as well as in saliva where the increases were much higher for the poliovirus than the E. coli antibodies. Yet another mother showed a certain increase of IgM but not of IgG antibodies in the milk. The uneven appearance of IgG and IgM antibodies in serum and secretions suggests local production. So do the differences of antibody avidities, the variations in IgG subclass distribution of antibodies and different patterns after isoelectric focusing (IEF)/immunoblotting analysis of antibody spectrotypes in secretions and serum. The study illustrates the variable patterns of compensatory increases of IgG and IgM antibodies which may occur in IgA deficiency. It also shows that the milk from IgA deficient mothers can still be rich in antibodies, in spite of the lack of secretory IgA.
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| 43. |
- Jayathilaka, P. A R D, et al.
(författare)
-
Dielectric relaxation, ionic conductivity and thermal studies of the gel polymer electrolyte system PAN/EC/PC/LiTFSI
- 2003
-
Ingår i: Solid State Ionics. - 0167-2738. ; 156, s. 179-195
-
Tidskriftsartikel (refereegranskat)abstract
- Dielectric relaxation, ionic conductivity and thermal properties have been measured for the gel polymer electrolyte system poly(acrylonitrile)/ethylene carbonate/propylene carbonate/lithium bis(trifluoromethanesulfone)imide (PAN/EC/PC/LiTFSI) and for its components in the frequency range from 1 MHz to 1.8 GHz and over a temperature range from -20 to 50 °C. DSC results suggest that EC/PC exists in two different environments within the gel network; as regions in which the EC/PC molecules subjected to pairing interactions by the CN group in PAN and also as regions consisting of "free" EC/PC molecules. Addition of PAN to the EC/PC/LiTFSI liquid electrolyte has increased the ionic conductivity. Out of the various PAN/LiTFSI composition ratios studied for the gel polymer electrolyte, the 6:1 composition ratio by weight gives the highest ionic conductivity. The room temperature (23 °C) conductivity of the gel electrolyte with this composition, PAN(15.4%)/EC(41.0%)/PC(41.0%)/LiTFSI(2.6%) (by weight) is 2.5 × 10-3 S cm-1. DSC results show that this composition has the most amorphous nature, above -105 °C. The ε″ spectra of gel electrolytes with various compositions show the presence of a high-frequency peak in the 0.5-GHz region attributed to the α relaxation process and a peak/shoulder in the 10-MHz region attributed to the ion-pair relaxation. Li+ ion transport probably takes place in the vicinity of the PAN chains and the ion-pair relaxation frequency appears to reflect the dynamic environment in which the cations migrate. However, the coupling between the conductivity and the α relaxations, attributed to EC/PC molecules, appears to be weak. A model has been presented according to which the Li+ ions in the gel electrolyte appears to be solvated by both PAN (through CN) and EC/PC. © 2003 Elsevier Science B.V. All rights reserved.
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| 44. |
- Jayathilaka, P. A R D, et al.
(författare)
-
Effect of nano-porous Al2O3 on thermal, dielectric and transport properties of the (PEO)9LiTFSI polymer electrolyte system
- 2002
-
Ingår i: Electrochimica Acta. - 0013-4686. ; 47:20, s. 3257-3268
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal, electrical conductivity and dielectric relaxation measurements have been performed on (PEO)9LiTFSI + 10 wt.% Al2O3 nano-porous polymer electrolyte system. It is observed that the conductivity enhances substantially due to the presence of the filler particles with different surface groups. The highest enhancement is found for the filler particles with acidic groups followed by basic, neutral, and weakly acidic. The results reveal that the filler particles do not interact directly with poly(ethelene) oxide (PEO) chains indicating that the main chain dynamics governing the ionic transport has not significantly affected due to the filler. The results are consistent with the idea that the conductivity enhancement is due to the creation of additional sites and favourable conduction pathways for ionic transport through Lewis acid-base type interactions between the filler surface groups and the ionic species. This is reflected as an increase in the mobility rather than an increase in the number of charge carriers. A qualitative model has been proposed to explain the results. © 2002 Elsevier Science Ltd. All rights reserved.
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| 45. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
The involvement of Aeromonas salmonicida virulence factors in bacterial translocation across the rainbow trout, Oncorhynchus mykiss (Walbaum), intestine.
- 2008
-
Ingår i: Journal of fish diseases. - : Wiley. - 0140-7775. ; 31:2, s. 141-51
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenic bacterium Aeromonas salmonicida is the causative agent of furunculosis, a lethal disease in salmonids. The mode of lateral transmission has not been conclusively defined, but A. salmonicida is able to translocate across the intestinal epithelium of salmonids, making the intestinal route a probable candidate. This study investigated some of the virulence mechanisms used by the bacteria to promote translocation. Intestinal segments were placed in modified Ussing chambers to investigate epithelial functions during exposure to bacterial factors. The factors were: extracellular products (ECP), lipopolysaccharide (LPS) or live or heat-inactivated A. salmonicida. Fluorescein isothiocynate (FITC)-labelling enabled detection of translocated bacteria by fluorometry. Live A. salmonicida translocated to a greater degree than heat-inactivated bacteria, suggesting that the bacteria utilize a heat sensitive surface-bound virulence factor which promotes translocation. The epithelium was negatively affected by ECP, manifested as decreased net ion transport, indicating a disturbance in ion channels or cell metabolism. LPS did not affect the epithelium in vitro when administered on the luminal side of the intestinal segment, but significantly increased epithelial translocation of fluorescent bacterial-sized microspheres when administered on the serosal side. This is suggested to be caused by increased transcellular transport, as the paracellular permeability was unaffected indicating maintained epithelial integrity.
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| 46. |
- Karunaratne, B. A., et al.
(författare)
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Effect of alumina filler on spherulite growth and ionic conductivity of PEO9(LiClO4) solid polymer electrolyte
- 2021
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Ingår i: Current Science. - : Current Science Association. - 0011-3891. ; 120:5, s. 900-906
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Tidskriftsartikel (refereegranskat)abstract
- The effect of incorporation of alumina on conductivity and in situ growth of spherulites in (PEO)(9)LiClO4 solid polymer electrolyte was studied using polarized microscopy, impedance and infrared spectroscopy. Fourfold enhancement in ionic conductivity correlated with increase in the amorphous nature of the polymer electrolyte was observed with the addition of 15 wt% of alumina having 5.5 nm pore size. The addition of 5 wt% of alumina with pore size <10 mu m, increased the ionic conductivity by nearly 3%. Filler particles may act as nuclei for the spherulites, while preventing the recrystallization tendency of the polymer and hence increase its conductivity.
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| 47. |
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| 48. |
- Kellner, E, et al.
(författare)
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Simple model of a raised bog
- 1997
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Ingår i: Annales Geophysicae, Supplement II. ; , s. C 295-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 49. |
- Kreuger, A., et al.
(författare)
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[Acute lymphatic leukemia in Swedish children 1968-2001. The marked improvement of the survival can be ascribed to successful treatment]
- 2004
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Ingår i: Lakartidningen. - 0023-7205. ; 101:48
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Tidskriftsartikel (refereegranskat)abstract
- This is a survey of acute lymphoblastic leukemia (ALL) in Swedish children from 1968 to 2001. The survival has increased from a few per cent to more than 80 per cent of children with ALL in these national complete patient materials. Changes in diagnosis and treatment are discussed as well as the importance of supportive care. The favorable results can almost certainly be ascribed to continuous cooperation between the Swedish pediatric departments, the Swedish Child Leukemia Group and international working groups.
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| 50. |
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