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| 3. |
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| 4. |
- Albinsson, I., et al.
(författare)
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Ion association effects and ionic conduction in polyalkalene modified polydimethylsiloxanes
- 1992
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Ingår i: Solid State Ionics. - : Elsevier. - 0167-2738 .- 1872-7689. ; 53-56:Part 2, s. 1044-1053
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Tidskriftsartikel (refereegranskat)abstract
- Poly (ethylene oxide) and poly (propylene oxide) modified poly (dimethyl siloxane) (PDMS) have been complexed with LiCF3SO3, NaCF3SO3 and KCF3SO3. In order to study ion association in these systems, the nondegenerate symmetric stretch (A1, SO3) Raman modes have been studied as a function of temperature at several different salt concentrations. Ionic conductivity has also been measured. For the poly (ethylene oxide) modified PDMS (PEO-PDMS), ether oxygen to metal ratios ranged from 12500:1 to 9:1. Changing the cation from Li+ to Na+ to K+ increases the conductivity of the complex. Plots of the molar conductivity versus salt concentration show that the characteristic shape and the region of increase in the molar conductivity is influenced most by the fraction of “free” ions which increases with increasing salt concentration. Charged triplets and contact ion-pairs are also present at the higher salt concentrations; the number of triplets increases with concentration and temperature. Non-VTF behaviour is observed. For the poly (propylene oxide) modified PDMS (PPO-PDMS) (with excess PPO), phase separation is observed when these triflate salts are complexed in. These solutions above and below the boundary layer have been studied by Raman spectroscopy revealing that the upper region is siloxane rich. The formation of the boundary layer is attributed to an increasing difference in surface tension between the PPO/salt/PPO-PDMS complexes and the separate PPO, PPO-PDMS components. The boundary layer moves up with increase in salt concentration. There is evidence of “free” ions, contact-ion pairs, triplets and aggregates. Values of conductivity of 2.2×10−6 and 1.6×10−5 S/cm are quoted for 293 K and 8 mol% LiCF3SO3 in respectively PPO-PDMS/PPO and PEO-PDMS/PEO. Both are better conductors than the corresponding 8 mol% PPG4000/LiCF3SO3 complex.
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| 5. |
- Arof, A. K., et al.
(författare)
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Polyacrylonitrile gel polymer electrolyte based dye sensitized solar cells for a prototype solar panel
- 2017
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 251, s. 223-234
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Tidskriftsartikel (refereegranskat)abstract
- Polyacrylonitrile (PAN) based gel polymer electrolytes (GPE) were prepared using lithium iodide (LiI), 1-butyl-3-methylimidazolium iodide (BMII) and tetrapropyl ammonium iodide (TPAI). The LiI mass fraction in the electrolyte was varied while keeping the masses of other components constant in order to enhance the solar cell performance. The addition of 4.61 wt.% LiI in the GPE increased the electrolyte room temperature ionic conductivity from (2.32 ± 0.02) to (3.91 ± 0.04) mS cm−1. The increase in conductivity with the addition of LiI salts was attributed to the increase in diffusion coefficient, mobility and number density of charge carriers as determined from Nyquist plot fitting. The incorporation of LiI salts in PAN-based GPE has enhanced the efficiency of the DSSC as expected. The best cell performance was obtained with an electrolyte containing 4.61 wt.% LiI sandwiched between a single mesoporous layer of TiO2 soaked in N3 dye sensitizer and a platinum counter electrode, which showed a power conversion efficiency (PCE) of (5.4 ± 0.1) % with a short circuit current density (Jsc) of (21.0 ± 1.1) mA cm−2, an open circuit voltage (Voc) of (0.48 ± 0.02) V and a fill factor (FF) of (53.4 ± 0.9) %. The DSSCs with 4.61 wt.% of LiI have been used to fabricate prototype solar panels for operating small devices. The panels were assembled using a number of cells, each having an area of 2 cm × 2 cm, connected in series and parallel. The panel, consisting of a set of eight cells in series which was connected in parallel with another set of eight cells in series, produces an average power conversion efficiency of (3.7 ± 0.2)% with a maximum output power of (17.1 ± 0.9) mW. © 2017 Elsevier Ltd
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| 6. |
- Bandara, Tmwj, et al.
(författare)
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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
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Ingår i: Journal of Materials Science-Materials in Electronics. - 0957-4522. ; 34:28
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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.
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| 7. |
- Buraidah, M. H., et al.
(författare)
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High efficient dye sensitized solar cells using phthaloylchitosan based gel polymer electrolytes
- 2017
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 245, s. 846-853
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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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| 8. |
- Dissanayake, M. A. K. L., et al.
(författare)
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High-efficiency dye-sensitized solar cells fabricated with electrospun PVdF-HFP polymer nanofibre-based gel electrolytes
- 2023
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Ingår i: Bulletin of Materials Science. - 0973-7669 .- 0250-4707. ; 46:2
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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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| 9. |
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| 10. |
- Jacobsson, Per, et al.
(författare)
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Ion association effects and phase separation in poly(propylene oxide) modified poly(dimethylsiloxane) complexed with triflate salts
- 1992
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Ingår i: Polymer. - : Elsevier. - 0032-3861 .- 1873-2291. ; 33:13, s. 2778-2783
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Tidskriftsartikel (refereegranskat)abstract
- Phase separation is observed in poly(propylene oxide) modified poly(dimethylsiloxane) (PPO-PDMS) with excess poly(propylene oxide) (PPO) when salts of MCF3SO3 (M = Li, Na) are added. The same behaviour is inferred for KCF3SO3. The solutions above and below the boundary layer have been studied by Raman spectroscopy and in particular by examining the non-degenerate, symmetric stretch (A1, SO3) Raman mode of the CF3SO3− anion. The upper part is siloxane rich; salt is present on both sides of the boundary layer with a much lower concentration in the upper part. The formation of the boundary layer is attributed to an increasing difference in surface tension between the PPO/salt/PPO-PDMS complexes and the separate PPO, PPO-PDMS components. The boundary layer moves up with increase in concentration. The number of ‘free’ ions decreases and ion association increases with increase in temperature. There is evidence of contact ion pairs, triplets and aggregates. Values of conductivity are quoted for 293 K.
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| 11. |
- Kuimova, M. K., et al.
(författare)
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Determination of the triplet state energies of a series of conjugated porphyrin oligomers
- 2007
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Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 6:6, s. 675-682
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Tidskriftsartikel (refereegranskat)abstract
- We report a systematic study of the photophysical parameters relevant to photodynamic therapy (PDT) by a new type of sensitizers, conjugated porphyrin oligomers. Due to the strong nonlinear properties of oligomers containing 2, 4 and 8 porphyrin units, these molecules are attractive candidates for PDT via multiphoton excitation. The triplet state energy levels for all molecules have been determined by the triplet quenching method, phosphorescence measurements and DFT calculations. We find that the triplet energies of all the oligomers are sufficient to generate singlet oxygen, > 94 kJ mol(-1). However, low singlet oxygen quantum yields are observed for the tetramer and the octamer, as compared to the conjugated dimer and monomeric porphyrin, reflecting the decrease in triplet yield. Thus the conjugated porphyrin dimer is the most promising core structure for PDT applications via multiphoton excitation.
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| 12. |
- Lundberg, Erik, 1981, et al.
(författare)
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Addressable molecular node assembly - high information density DNA nanostructures
- 2008
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Ingår i: Nucleic acids symposium series (2004). - 1746-8272. ; :52, s. 683-684
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Tidskriftsartikel (refereegranskat)abstract
- The inherent self-assembly properties of DNA make it ideal in nanotechnology. We present a fully addressable DNA nanostructure with the smallest possible unit cell, a hexagon with a side-length of only 3.4 nm.(2,3) Using novel three-way oligonucleotides, where each side has a unique double-stranded DNA sequence that can be assigned a specific address, we will build a non-repetitive two-dimensional grid.
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| 13. |
- Salve, Maruti V., et al.
(författare)
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Highly Crystalline and Stoichiometric Growth of CdTe by Cost-Effective Hydrothermal Technique
- 2024
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Ingår i: JOURNAL OF ELECTRONIC MATERIALS. - 0361-5235 .- 1543-186X.
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Tidskriftsartikel (refereegranskat)abstract
- CdTe powder samples have been synthesized using a hydrothermal approach, employing cadmium acetate and tellurium dioxides as sources of Cd and Te, respectively. NaBH4 was utilized as the reducing agent, and double-distilled water was used as the solvent in the synthesis process. The effect of annealing on the synthesized samples was investigated. The samples have been characterized by x-ray powder diffraction, Raman spectroscopy, UV-Vis-NIR spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and x-ray photoelectron spectroscopy. The electrical properties (current-voltage and capacitance-voltage) of the as-prepared and annealed CdTe pellets were investigated. These findings indicate that annealing can lead to improvements in crystallinity, crystallite size, and electrical conductance. This paper presents a simple, cost-effective, and versatile method for producing significant amounts of CdTe nanostructure powders with properties suitable for use in the fabrication of CdS/CdTe solar cells.
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| 14. |
- Shah, S., et al.
(författare)
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Plasmonic effects of quantum size metal nanoparticles on dye-sensitized solar cell
- 2017
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Ingår i: Optical Materials Express. - : The Optical Society. - 2159-3930. ; 7:6, s. 2069-2083
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Tidskriftsartikel (refereegranskat)abstract
- Gel polymer electrolytes (GPEs) based on poly(ethylene oxide) (PEO) and phthaloyl chitosan (PhCh) for dye-sensitized solar cells (DSSCs) have been synthesized and characterized. The GPEs have been prepared using different weight fractions of PEO and PhCh that have been added to a fixed composition solution of tetrapropylammonium iodide (TPAI), dimethylformamide (DMF) and iodine (I-2) crystals. The ionic conductivity behavior of prepared GPEs was studied using impedance spectroscopy. The sample having 70 wt.% PEO and 30 wt.% PhCh showed the highest ionic conductivity of 7.36 mS cm(-1) at room temperature. The photoanode of the DSSC consists of two TiO2 layers. The first or compact layer has a thickness of similar to 5 mu m and the TiO2 nanoparticles have an average size of 14 nm. The second layer of TiO2 nanoparticles has an average size of 21 nm. In order to adsorb dye molecules, the TiO2 photoanodes were soaked in anthocyanin and ruthenium 535 (N3) dye solutions. The GPE has been deposited between the dye/ TiO2 photoanode and platinum (Pt) counter electrode in a sandwich-like structure. Results showed that the fabricated DSSC with an electrolyte containing 70 wt.% PEO: 30 wt.% PhCh exhibited the highest efficiency for both anthocyanin and N3 dyes and the efficiency and ionic conductivity trend versus PEO content are similar. On addition of different amounts of Ag nanoparticles (0, 10, 20, 30, 40 mu L), with average size of 10 nm to the second TiO2 layer, the performance of DSSCs with anthocyanin sensitizer and N3 dye improved. The cell with anthocyanin/(TiO2 + 10 mu L Ag nanoparticles) showed a 21%, 17.2% and 39.6% increase in short circuit current density (J(sc)), fill factor (FF), and light to electricity conversion efficiency (.) respectively compared to the cell without Ag nanoparticle. The DSSC fabricated with TiO2 photoanode containing 20 mu L Ag nanoparticles soaked in N3 dye exhibits Jsc, FF, and. of 15.24 mA cm(-2), 57% and 5.21% respectively. The incorporation of Ag nanoparticles has resulted in a 17% and 13% increase in Jsc, and., respectively, for N3 based cells. This performance enhancement with the addition of Ag nanoparticles can be attributed to improvement of light scattering and charge transport as a result of plasmonic resonance. (C) 2017 Optical Society of America
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| 15. |
- Shah, S., et al.
(författare)
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Plasmonic effects of quantum size metal nanoparticles on dye-sensitized solar cell
- 2017
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Ingår i: Optical Materials Express. - 2159-3930. ; 7:6, s. 2069-2083
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Tidskriftsartikel (refereegranskat)abstract
- Gel polymer electrolytes (GPEs) based on poly(ethylene oxide) (PEO) and phthaloyl chitosan (PhCh) for dye-sensitized solar cells (DSSCs) have been synthesized and characterized. The GPEs have been prepared using different weight fractions of PEO and PhCh that have been added to a fixed composition solution of tetrapropylammonium iodide (TPAI), dimethylformamide (DMF) and iodine (I-2) crystals. The ionic conductivity behavior of prepared GPEs was studied using impedance spectroscopy. The sample having 70 wt.% PEO and 30 wt.% PhCh showed the highest ionic conductivity of 7.36 mS cm(-1) at room temperature. The photoanode of the DSSC consists of two TiO2 layers. The first or compact layer has a thickness of similar to 5 mu m and the TiO2 nanoparticles have an average size of 14 nm. The second layer of TiO2 nanoparticles has an average size of 21 nm. In order to adsorb dye molecules, the TiO2 photoanodes were soaked in anthocyanin and ruthenium 535 (N3) dye solutions. The GPE has been deposited between the dye/ TiO2 photoanode and platinum (Pt) counter electrode in a sandwich-like structure. Results showed that the fabricated DSSC with an electrolyte containing 70 wt.% PEO: 30 wt.% PhCh exhibited the highest efficiency for both anthocyanin and N3 dyes and the efficiency and ionic conductivity trend versus PEO content are similar. On addition of different amounts of Ag nanoparticles (0, 10, 20, 30, 40 mu L), with average size of 10 nm to the second TiO2 layer, the performance of DSSCs with anthocyanin sensitizer and N3 dye improved. The cell with anthocyanin/(TiO2 + 10 mu L Ag nanoparticles) showed a 21%, 17.2% and 39.6% increase in short circuit current density (J(sc)), fill factor (FF), and light to electricity conversion efficiency (.) respectively compared to the cell without Ag nanoparticle. The DSSC fabricated with TiO2 photoanode containing 20 mu L Ag nanoparticles soaked in N3 dye exhibits Jsc, FF, and. of 15.24 mA cm(-2), 57% and 5.21% respectively. The incorporation of Ag nanoparticles has resulted in a 17% and 13% increase in Jsc, and., respectively, for N3 based cells. This performance enhancement with the addition of Ag nanoparticles can be attributed to improvement of light scattering and charge transport as a result of plasmonic resonance.
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| 16. |
- Shamsuddin, L., et al.
(författare)
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Perovskite solar cells using polymer electrolytes
- 2017
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Ingår i: Molecular Crystals and Liquid Crystals. - : Informa UK Limited. - 1542-1406 .- 1563-5287. ; 655:1, s. 181-194
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with the characterization of methylammonium lead iodide (MAPbI3) material and the fabrication of perovskite solar cells using gel polymer electrolyte as the charge transport medium. The crystalline lead–based perovskite has been verified by x-ray diffraction (XRD). The [100], [200], [210], [211], [220], [300] and [222] reflection planes can be observed at 2θ angles of 14.10°, 28.35°, 31.90°, 34.95°, 40.40°, 43.15° and 50.20°, indicating a cubic crystal symmetry for CH3NH3PbI3. EDX spectrum showed a Pb:I ratio of approximately 1:3 as in CH3NH3PbI3. The band gap for lead-based perovskite is 1.45eV estimated from UV-Vis absorption spectroscopy. The nanocrystalline MAPbI3 have been observed using field emission scanning electron microscopy (FESEM), where the average cuboid size of perovskite nanocrystals is 380nm. The cell have been fabricated using gel polymer electrolyte with composition 17.02wt.% PVA–13.93wt.% TBAI–0.96wt.% I2– 68.09wt.% DMF. The cell exhibits a power conversion efficiency (PCE) of 1.28% with open circuit voltage (Voc) 0.58mV, short circuit current density (Jsc) 3.74mA cm−2 and fill factor (FF) 59.18%.
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| 17. |
- Tumpane, John, 1983, et al.
(författare)
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Triplex addressability as a basis for functional DNA nanostructures
- 2007
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 7:12, s. 3832-3839
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present the formation of a fully addressable DNA nanostructure that shows the potential to be exploited as, for example, an information storage device based on pH-driven triplex strand formation or nanoscale circuits based on electron transfer, The nanostructure is composed of two adjacent hexagonal unit cells (analogous to naphthalene) in which each of the eleven edges has a unique double-stranded DNA sequence, constructed using novel three-way oligonucleotides. This allows each ten base-pair side, just 3.4 nm in length, to be assigned a specific address according to its sequence. Such constructs are therefore an ideal precursor to a nonrepetitive two-dimensional grid on which the "addresses" are located at a precise and known position. Triplex recognition of these addresses could function as a simple yet efficient means of information storage and retrieval. Future applications that may be envisaged include nanoscale circuits as well as subnanometer precision in nanoparticle templating. Characterization of these precursor nanostructures and their reversible targeting by triplex strand formation is shown here using gel electrophoresis, atomic force microscopy, and fluorescence resonance energy transfer (FRET) measurements. The durability of the system to repeated cycling of pH switching is also confirmed by the FRET studies.
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| 18. |
- Ukarande, Aparna, et al.
(författare)
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Investigation of electrodeposited CdTe thin films for solar cell development
- 2023
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Ingår i: Journal of Materials Science: Materials in Electronics. - 1573-482X .- 0957-4522. ; 34:27
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Tidskriftsartikel (refereegranskat)abstract
- We report the growth of CdTe thin films using a wet-chemical electrochemical technique in an aqueous bath. The effect of bath temperature is investigated in detail on the various properties of the sample and the optoelectronic performance of the solar cell devices. A three-electrode technique was employed to deposit the samples at − 0.7 V concerning the Ag/AgCl reference electrode optimized by cyclic voltammetry measurements. The sample annealed at 450 °C for 20 min exhibited a polycrystalline cubic crystal structure of CdTe with an optical energy bandgap of ~ 1.45 eV. The Raman analysis reveals the growth of highly polycrystalline CdTe. All samples were highly compact and well-adherent to the substrate without pinholes. The annealed sample grown at a bath temperature of 50 °C exhibited a large globular grain size of ~ 1 μm. Furthermore, the stoichiometric (50:50) growth of Cd and Te was confirmed using EDAX for the sample grown at a bath temperature of 50 °C. A typical solar cell device, glass/FTO/CdS/CdTe/Au, was measured under dark and illuminated conditions with an input intensity of 100 mW/cm2 and showed a fill factor of ~ 50% and an efficiency of 2.65%. The solar cell parameters can be further improved by optimizing the surface treatment conditions using appropriate oxidizing and reducing reagents.
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| 19. |
- Zhu, Bin, et al.
(författare)
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Intermediate temperature fuel cells using alkaline and alkaline earth fluoride-based electrolytes
- 2000
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Ingår i: Solid State Ionics. - 0167-2738 .- 1872-7689. ; 135:04-jan, s. 503-512
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Tidskriftsartikel (refereegranskat)abstract
- Investigation of fuel cell applications using fluoride electrolytes, especially alkaline and alkaline earth fluorides, is a very new subject. Actually, most of the fluorides can function as fuel cell electrolytes, but the alkaline and alkaline earth fluorides are specially interesting since in composite materials they exhibit excellent performance for fuel cell electrolytes. Among the alkaline earth fluoride fuel cells, the best performance was achieved thus far for the fuel cell using the NaF-BaF2-Al2O3 electrolyte and LiNiO2 anode supported technique: it reached a power density of about 110 mW cm(-2) at a current density of 250 mA cm(-2) at 750 degreesC. Both proton and oxygen ionic conduction may exist in the alkaline earth fluorides since, during the fuel cell operation, water was observed at both the anode and the cathode, but, in most cases, water was formed at the cathode side mainly. Thus, proton conduction predominates, resulting in excellent fuel cell performances. A possible ionic transport mechanism is also discussed.
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