| 1. |
- Bandara, Tmwj, et al.
(författare)
-
Efficiency enhancement and chrono-photoelectron generation in dye-sensitized solar cells based on spin-coated TiO2 nanoparticle multilayer photoanodes and a ternary iodide gel polymer electrolyte
- 2023
-
Ingår i: Journal of Materials Science-Materials in Electronics. - 0957-4522. ; 34:28
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of the thickness of a multilayer TiO2 photoanode on the performance of a dye-sensitized solar cell (DSC) made with a polyethylene oxide-based gel polymer electrolyte containing ternary iodides and performance enhancer 4-tert-butylpyridine is studied. Multilayer photoanodes consisting of up to seven layers of TiO2 nano-particles (13 nm and 21 nm) are prepared by spin coating of successive layers. XRD results confirm the predominant presence of the anatase phase of TiO2 in the multilayer structure after sintering. The SEM images reveal the formation of a single TiO2 film upon sintering due to merging of individually deposited layers. The photocurrent density (J(SC)) and the efficiency increase with the number of TiO2 layers exhibiting the maximum efficiency and J(SC) of 5.5% and 12.5 mA cm(-2), respectively, for the 5-layered electrode of total thickness 4.0 mu m with a 9.66 x 10(-8) mol cm(-2) surface dye concentration. The present study introduces a method of determining the rate of effective photoelectron generation and the average time gap between two successive photon absorptions where the respective results are 1.34 molecule(-1) s(-1) and 0.74 s for the most efficient cell studied in this work.
|
|
| 2. |
- Bandara, Tmwj, et al.
(författare)
-
Nano structured diatom frustules incorporated into TiO2 photoelectrodes to enhance performance of quasi-solid-state dye-sensitized solar cells
- 2023
-
Ingår i: Optical Materials. - 0925-3467. ; 146
-
Tidskriftsartikel (refereegranskat)abstract
- Diatom frustules are incorporated into multilayer photoelectrodes intending to enhance efficiency in dyesensitized solar cells utilizing their light interaction properties. A specific, but ubiquitous in all oceans, pennate-type diatom frustules were used to form the composite layers. Single, double, and triple-layer photoelectrodes were constructed with pure TiO2 (control measurements) as well as with a TiO2/diatom frustule composite. The electrodes were prepared using TiO2 nanoparticles of two sizes (13 and 21 nm) and were analyzed using UV visible absorption and XRD spectra. The morphology of frustules and electrodes were analyzed using scanning electron microscopy. The performance for each photoanode configuration was measured by assembling photoelectrochemical solar cells fabricated with a Pt counter electrode and a gel polymer electrolyte that excludes volatile solvents. The efficiency of the control cell is 3.37%. After replacing the topmost TiO2 layer with a TiO2/diatom frustule composite layer, efficiency increases to 6.78%. This is an impressive efficiency enhancement of 101%. The short circuit current density of frustule-incorporated threelayer cells is 18.1 mA cm-1 while for the control cell it is 8.98 mA cm-1. The enhanced efficiency of cells made with TiO2/diatom frustule composite electrodes and a polyethylene oxide-based gel polymer electrolyte can be attributed to the improved light absorption by the photoanode due to optical scattering and light-trapping effects caused by the presence of diatom frustules. Frustules also can assist in enhancing dye adsorption by increasing the effective specific surface area of the composite photoelectrode due to their nanoporous structure.
|
|
| 3. |
- Abrahamsson, Kate, 1959, et al.
(författare)
-
Transient reduction of human left ventricular mass in carnitine depletion induced by antibiotics containing pivalic acid.
- 1995
-
Ingår i: British heart journal. - : BMJ. - 0007-0769. ; 74:6, s. 656-9
-
Tidskriftsartikel (refereegranskat)abstract
- To study the effect of induced carnitine depletion on myocardial structure and function.7 healthy adult volunteers given 1200 mg pivmecillinam per day for 7-8 weeks were studied by echocardiography before and after 7-8 weeks of treatment and a 15 months follow up after the treatment period.Teaching hospital.Carnitine concentration in serum, urine, and muscle and echocardiographic measurements.After 7-8 weeks of treatment the median free serum carnitine concentration was reduced to 7% and the median total muscle carnitine concentration to 46% of the pretreatment levels. The median diastolic interventricular septum thickness decreased by 14% (mean 26%, P = 0.028) and the median left ventricular mass by 10% (mean 20%, P = 0.018). Fifteen months later these dimensions had increased but not completely returned to pretreatment values.Extended treatment with pivalic acid containing antibiotics causes carnitine depletion which may lead to changes in cardiac structure.
|
|
| 4. |
|
|
| 5. |
- Bandara, T M W J, 1968, et al.
(författare)
-
Determination of charge carrier transport parameters in a polymer electrolyte intended for Li-ion batteries using electrochemical impedance analysis
- 2020
-
Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1433-0768 .- 1432-8488. ; 24:5, s. 1207-1216
-
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.
|
|
| 6. |
- 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.
|
|
| 7. |
- Bandara, Tmwj, et al.
(författare)
-
Novel photo-voltaic device based on Bi1-xLaxFeO3 perovskite films with higher efficiency
- 2019
-
Ingår i: Journal of Materials Science-Materials in Electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 30:2, s. 1654-1662
-
Tidskriftsartikel (refereegranskat)abstract
- Photovoltaic cells using polycrystalline La substituted bismuth iron oxide, Bi1-xLaxFeO3, (0.1x0.4), films as the light harvesting component were investigated in this work. A novel cell set-up utilizing a double layered TiO2 film as top contact and a thin layer of quasi-solid polymer electrolyte as back contact was used and a significant enhancement in cell efficiency was observed for assemblies based on x0.2 samples, coincident with a structural transition of Bi1-xLaxFeO3 from ferroelectric to non-ferroelectric. The power conversion efficiency of the PV device was 0.13% for the cell with x=0.2at 1 sun irradiation. The short circuit current density for this La composition was 0.35mAcm(-2). A hysteretic behaviour was observed for higher La compositions when the scanning is from open-circuit (OP) to short-circuit (SC) which may be attributed to polarization effects. The results at x0.2 show an improved performance with respect to BiFeO3 based systems, suggesting the stabilization of the non-ferroelectric crystal structure leads either to a more efficient separation of photo-generated electron-hole pairs and/or enhanced charge transport. The findings represent a step towards the realisation of facile to fabricate, inorganic solid state photovoltaic devices.
|
|
| 8. |
- 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.
|
|
| 9. |
|
|
| 10. |
|
|
