| 61. |
- Nagaraju, D. H., et al.
(författare)
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Charge Storage Capacity of Renewable Biopolymer/Conjugated Polymer Interpenetrating Networks Enhanced by Electroactive Dopants
- 2014
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Ingår i: Advanced Energy Materials. - : Wiley-VCH Verlag. - 1614-6832 .- 1614-6840. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Renewable materials are requested for large scale electrical storage, a coming necessity with the growth of intermittent solar and wind renewable electricity generation. Biopolymers are a source of inexpensive materials, in particular through the use of black liquor from paper production, a waste product. Interpenetrating networks of the biopolymer lignosulfonate (Lig) and conjugated polymer polypyrrole (Ppy) are synthesized by galvanostatic polymerization from pyrrole/lignosulfonate mixture in acidic aqueous electrolyte. Methoxy and phenolic functional group present in the non-conducting lignosulfonate are converted to quinone groups. The redox chemistry of quinones is used for charge storage, along with charge storage in polypyrrole. A large variation of the electrochemical activity between lignosulfonates obtained from different sources is observed. The charge storage capacities are significantly enhanced by also including another electroactive dopant, anthraquinone sulfonate (AQS). AQS redox peaks act as an internal reference (standard) to probe the redox electrochemistry of Lig. The synthesized Ppy(Lig) and Ppy(Lig-AQS) electrodes are characterized by cyclic voltammetry, galvanostatic charge-discharge cycling, electrochemical quartz crystal microbalance, and atomic force microscopy.
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| 62. |
- O Reese, Matthew, et al.
(författare)
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Consensus stability testing protocols for organic photovoltaic materials and devices
- 2011
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Ingår i: SOLAR ENERGY MATERIALS AND SOLAR CELLS. - : Elsevier Science B.V., Amsterdam.. - 0927-0248. ; 95:5, s. 1253-1267
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Tidskriftsartikel (refereegranskat)abstract
- Procedures for testing organic solar cell devices and modules with respect to stability and operational lifetime are described. The descriptions represent a consensus of the discussion and conclusions reached during the first 3 years of the international summit on OPV stability (ISOS). The procedures include directions for shelf life testing, outdoor testing, laboratory weathering testing and thermal cycling testing, as well as guidelines for reporting data. These procedures are not meant to be qualification tests, but rather generally agreed test conditions and practices to allow ready comparison between laboratories and to help improving the reliability of reported values. Failure mechanisms and detailed degradation mechanisms are not covered in this report.
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| 63. |
- Pal, S. K., et al.
(författare)
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Geminate Charge Recombination in Polymer/Fullerene Bulk Heterojunction Films and Implications for Solar Cell Function
- 2010
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 132:35, s. 12440-12451
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the influence of three different fullerene derivatives on the charge generation and recombination dynamics of polymer/fullerene bulk heterojunction (BHJ) solar cell blends. Charge generation in APFO3/[70]PCBM and APFO3/[60]PCBM is very similar and somewhat slower than charge generation in APFO3/[70]BTPF. This difference qualitatively matches the trend in free energy change of electron transfer estimated from the LUMO energies of the polymer and fullerene derivatives. The first order (geminate) charge recombination rate is significantly different for the three fullerene derivatives studied and increases in the order APFO3/[70]PCBM
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| 64. |
- Pranculis, Vytenis, et al.
(författare)
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Charge Carrier Generation and Transport in Different Stoichiometry APFO3:PC61BM Solar Cells
- 2014
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 136:32, s. 11331-11338
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we studied carrier drift dynamics in APFO3:PC61BM solar cells of varied stoichiometry (2:1, 1:1, and 1:4 APFO3:PC61BM) over a wide time range, from subpicoseconds to microseconds with a combination of ultrafast optical electric field probing and conventional transient integrated photocurrent techniques. Carrier drift and extraction dynamics are strongly stoichiometry dependent: the speed of electron or hole drift increases with higher concentration of PC61BM or polymer, respectively. The electron extraction from a sample with 80% PC61BM takes place during hundreds of picoseconds, but slows down to sub-microseconds in a sample with 33% PC61BM. The hole extraction is less stoichiometry dependent: it varies form sub-nanoseconds to tens of nanoseconds when the PC61BM concentration changes from 33% to 80%. The electron extraction rate correlates with the conversion efficiency of solar cells, leading to the conclusion that fast electron motion is essential for efficient charge carrier separation preventing their geminate recombination.
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| 65. |
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| 66. |
- Rizzo, Aurora, et al.
(författare)
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White Light with Phosphorescent Protein Fibrils in OLEDs
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:6, s. 2225-2230
-
Tidskriftsartikel (refereegranskat)abstract
- Red and yellow phosphorescent insulin amyloid fibrils are used as guest-emitting species within a blue-emitting polyfluorene matrix in light-emitting diodes. The integration of the phosphorescent Ir-complex into the amyloid structures strongly improves the triplet exciton confinement and allows the fabrication of white-emitting device with a very low loading of phosphorescent complex. The overall performances of the devices are improved in comparison with the corresponding bare Ir-complexes. This approach opens a way to explore novel device architectures and to understand the exciton/charge transfer dynamics in phosphorescent light emitting diodes.
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| 67. |
- Sandström, Andreas, et al.
(författare)
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Separating Ion and Electron Transport: The Bilayer Light-Emitting Electrochemical Cell
- 2010
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Ingår i: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - : ACS American Chemical Society. - 0002-7863 .- 1520-5126. ; 132:19, s. 6646-
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Tidskriftsartikel (refereegranskat)abstract
- The current generation of polymer light-emitting electrochemical cells (LECs) suffers from insufficient stability during operation. One identified culprit is the active material, which comprises an intimate blend between an ion-conducting electrolyte and an electron-transporting conjugated polymer, as it tends to undergo phase separation during long-term operation and the intimate contact between the ion- and electron-transporting components provokes side reactions. To address these stability issues, we present here a bilayer LEC structure in which the electrolyte is spatially separated from the conjugated polymer. We demonstrate that employing this novel device structure, with its clearly separated ion- and electron-transport paths, leads to distinctly improved LEC performance in the form of decreased turn-on time and improved light emission. We also point out that it will allow for the utilization of combinations of active materials having mutually incompatible solubilities.
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| 68. |
- Schmidt, Daniel, et al.
(författare)
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Optical properties of hybrid titanium chevron sculptured thin films coated with a semiconducting polymer
- 2011
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Ingår i: THIN SOLID FILMS. - : ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND. - 0040-6090. ; 519:9, s. 2645-2649
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Tidskriftsartikel (refereegranskat)abstract
- Optical and structural properties of a hybrid metallic chevron sculptured thin film from titanium coated with the semiconducting polymer poly(3-dodecylthiophene) (P3DDT) are reported. The nanostructured thin film with two subsequent layers of oppositely slanted nanocolumns was fabricated by glancing angle deposition and coated with P3DDT by a spin-cast process. Spectroscopic generalized ellipsometry is employed to determine geometrical structure properties and the anisotropic optical constants of the coated and uncoated film in the spectral range from 400 to 1700 nm. The nanostructured thin films before and after hybridization show highly anisotropic optical properties. The complex refractive indices along major polarizability directions of the hybridized chevrons are increased in the entire investigated spectral range with respect to the as-deposited chevrons. Changes in birefringence and dichroism upon polymer infiltration are observed.
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| 69. |
- Sobkowiak, Marek, et al.
(författare)
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Amperometric detection of iron (III) on electroconductive hydrogel based on polypyrrole and alkoxysulfonated poly(3,4-ethylenedioxythiophene) (PEDOT-S)
- 2014
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 194, s. 170-175
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Tidskriftsartikel (refereegranskat)abstract
- A polymeric conducting hydrogel of autopolymerized polypyrrole (PPY) and poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S) cast-deposited on a glassy carbon electrode is demonstrated to be an efficient electrocatalyst for the fairly irreversible, and often irreproducible, reduction of Fe(Ill) at the bare substrate. Sensitive amperometric monitoring of Fe(III) is then possible without the need for oxygen removal at the fairly positive polarization potential of 0.3 V vs. Ag/AgCl in acidic electrolyte (0.1 M HClO4). The sensor shows a linear current response over a concentration range exceeding two orders of magnitude (2.5-500 mu M, R-2 = 0.9998). The detection limit (3 sigma) was estimated to be 0.8 mu M, and the sensitivity factor was 0.28 mu A mu M cm(-2), which is approximately 23 times higher than for the unmodified electrode under the same experimental conditions.
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| 70. |
- Sobkowiak, Marek, et al.
(författare)
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Electrochemistry and Ion Sensing Properties of Conducting Hydrogel Layers Based on Polypyrrole and Alkoxysulfonated Poly(3,4-ethylenedioxythiophene) (PEDOT-S)
- 2014
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Ingår i: Electroanalysis. - : Wiley-VCH Verlag. - 1040-0397 .- 1521-4109. ; 26:4, s. 739-747
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Tidskriftsartikel (refereegranskat)abstract
- Acidic aqueous solutions containing pyrrole and alkoxysulfonated PEDOT derivative (PEDOT-S) were found to undergo polymerization in the absence of an external oxidizing agent. The product was a nearly black-colored conducting hydrogel that after separation could be dispersed in water or acetone. The suspensions could be used to deposit cast films on a polycrystalline gold electrode. The polymer modified electrode showed a nearly Nernstian potentiometric response to Ag+ cations in the concentration range of 10(-5)-10(-1)M with the slope of 54mV/decade. The response was specific to Ag+ compared to a series of alkali and transition-metal cations (pK(Ag/M)greater than3.7).
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