| 31. |
- Inganäs, Olle, et al.
(författare)
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Recent progress in thin film organic photodiodes
- 2001
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Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 121:1-3, s. 1525-1528
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Tidskriftsartikel (refereegranskat)abstract
- We review current developments in organic photodiodes, with special reference to multilayer thin film optics, and modeling of organic donor-acceptor photodiodes. We indicate possibilities to enhance light absorption in devices by nanopatterning as well as by blending, and also discuss materials science issues of nanostructure in blends and in vertically stratified multilayer devices. Our current best devices have external efficiencies of 30-50% in between 400-600 nm, and show fill factors of 0.54 illuminated under weak monochromatic light.
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| 32. |
- Jager, EWH, et al.
(författare)
-
Microfabricating conjugated polymer actuators
- 2000
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 290:5496, s. 1540-1545
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Forskningsöversikt (refereegranskat)abstract
- Conjugated polymer actuators can be operated in aqueous media, which makes them attractive for laboratories-on-a-chip and applications under physiological conditions. One of the most stable conjugated polymers under these conditions is polypyrrole, which can be patterned by means of standard photolithography. Polypyrrole-gold bilayer actuators that bend out of the plane of the wafer have been microfabricated in our laboratory. These can be used to move and position other microcomponents. Here we review the current status of these microactuators, outlining the methods used to fabricate them. We describe the devices that have been demonstrated as well as some potential future applications.
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| 33. |
- Jager, Edwin, 1973-, et al.
(författare)
-
Microrobots for Micrometer-Size Objects in Aqueous Media : Potential Tools for Single-Cell Manipulation
- 2000
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 288:5475, s. 2335-2338
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Tidskriftsartikel (refereegranskat)abstract
- Conducting polymers are excellent materials for actuators that are operated in aqueous media. Microactuators based on polypyrrole-goldbilayers enable large movement of structures attached to theseactuators and are of particular interest for the manipulationof biological objects, such as single cells. A fabrication methodfor creating individually addressable and controllable polypyrrole-goldmicroactuators was developed. With these individually controlledmicroactuators, a micrometer-size manipulator, or microroboticarm, was fabricated. This microrobotic arm can pick up, lift,move, and place micrometer-size objects within an area of about250 micrometers by 100 micrometers, making the microrobot an excellenttool for single-cell manipulation.
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| 34. |
- Jager, Edwin, 1973-, et al.
(författare)
-
Perpendicular Actuation with Individually Controlled Polymer Microactuators
- 2001
-
Ingår i: Advanced Materials. - 0935-9648 .- 1521-4095. ; 13:1, s. 76-79
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Tidskriftsartikel (refereegranskat)abstract
- Actuator systems based on conducting polymers, such as polypyrole, with which three-dimensional movement can be controlled, are described. The Figure shows a combination of two such microactuators which are used to “kick” a glass bead across the surface of a silicon wafer. The microfabrication methods used to produce the systems are described and the potential uses, for example microrobotic arms, discussed.
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| 35. |
- Jager, Edwin W.H., et al.
(författare)
-
The cell clinic : closable microvials for single cell studies
- 2002
-
Ingår i: Biomedical microdevices (Print). - 1387-2176 .- 1572-8781. ; 4:3, s. 177-187
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Tidskriftsartikel (refereegranskat)abstract
- We present the development of a cell clinic. This is a micromachined cavity, or microvial, that can be closed with a lid. The lid is activated by two polypyrrole/Au microactuators. Inside the microvials two Au electrodes have been placed in order to perform impedance studies on single or a small number of cells. We report on impedance measurements on Xenopus leavis melanophores. We could measure a change in the impedance upon cell spreading and identify intracellular events such as the aggregation of pigment granules. The electrical data is correlated to optical microscopy.
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| 36. |
- Johansson, DM, et al.
(författare)
-
Influence of polymerization temperature on molecular weight, photoluminescence, and electroluminescence for a phenyl-substituted poly(p-phenylenevinylene)
- 2001
-
Ingår i: Macromolecules. - 0024-9297 .- 1520-5835. ; 34:11, s. 3716-3719
-
Tidskriftsartikel (refereegranskat)abstract
- We present the synthesis and characterization of poly(2-(2",5'-bis(2"-ethylhexyloxy)phenyl)-1,4-phenylenevinylene) (BEHP-PPV) polymerized at different temperatures. The photoluminescence efficiencies in the solid state of BEHP-PPV obtained at 144 and 0 degreesC are 28% and 60%, respectively. H-1 NMR measurements showed a lower concentration of structural defects for BEHP-PPV obtained at lower temperatures, which can explain the increased photoluminescence efficiencies for these polymers. Polymerization temperatures below 0 degreesC decrease the molecular weight without changing the photoluminescence efficiency to any large extent. The electroluminescence efficiencies follow the trend in the photoluminescence efficiencies.
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| 37. |
- Johansson, D.M., et al.
(författare)
-
Convenient synthetic route to poly(p-phenylene-1,2-diphenylvinylenes)
- 2000
-
Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 113:3, s. 293-297
-
Tidskriftsartikel (refereegranskat)abstract
- The synthesis and characterization of two soluble poly(p-phenylenevinylene)s substituted with phenyl groups on the vinylene moiety is reported. The polymers are poly(1,4-phenylene-1,2-diphenylvinylene) (PPV-DP) and poly(1,4-phenylene-1,2-(3'-(2?-ethylhexyloxy))-diphenylvinylene) (PPV-mEHDP). The monomers containing chloromethyl groups were polymerized with excess potassium tert-butoxide in dioxane at room temperature. The polymerization conditions are optimized. The photoluminescence (PL) properties of the polymers showed an increase in the PL efficiency in film from 19% for PPV-DP to 37% for PPV-mEHDP. Both polymers emitted green light with higher intensity in film than in solution.
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| 38. |
- Johansson, D.M., et al.
(författare)
-
Synthesis and characterisation of polyfluorenes with light-emitting segments
- 2001
-
Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 121:1-3, s. 1761-1762
-
Tidskriftsartikel (refereegranskat)abstract
- We present the synthesis and characterisation of two copolymers. They consists of poly(9-hexyl-9-(2'-ethylhexyl)fluorene) (HEH-PF) with a small amount of another polymer with a narrow band-gap. The synthetic route was designed to allow the incorporation of only one low band-gap segment per polymer chain. Photoluminescence measurements showed that energy transfer from the PF-segments to the low band-gap segments, did occur. In the solid state, all emissions were detected from the low band-gap segments with photoluminescence quantum yields up to 68%. One copolymer showed a low threshold for lasing (2 µJ/cm2) in a microcavity device.
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| 39. |
- Johansson, D.M., et al.
(författare)
-
Synthesis and characterization of highly soluble phenyl-substituted poly(p-phenylenevinylenes)
- 2000
-
Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 33:7, s. 2525-2529
-
Tidskriftsartikel (refereegranskat)abstract
- We present the synthesis and characterization of soluble, high molecular weight phenyl-substituted poly(p-phenylenevinylenes). The studied polymers are poly(2-(2',5'-bis(2?-ethylhexyloxy)phenyl)- 1,4-phenylenevinylene) (BEHP-PPV) and copolymers of BEHP-PPV and poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV). Their photoluminescence and electroluminescence have been examined as well as their stability to air and light. The polymers emitted green and yellow light. Stability measurements showed increased stability compared to some previously known substituted PPVs.
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| 40. |
- Johansson, DM, et al.
(författare)
-
Synthesis and characterization of polyfluorenes with light-emitting segments
- 2001
-
Ingår i: Macromolecules. - 0024-9297 .- 1520-5835. ; 34:6, s. 1981-1986
-
Tidskriftsartikel (refereegranskat)abstract
- Two new polymers consisting of poly(9-(2'-ethylhexyl)-9-hexylfluorene) (EHH-PF) with a small amount of substituted poly(p-phenylenevinylene) (PPV) segments have been synthesized and characterized. The synthetic route was designed to allow the incorporation of only one (or zero) PPV segments per polymer chain. Photoluminescence measurements showed that energy transfer from the PF segments to the more narrow band-gap PPV segments did occur, both in solution and in film. In the solid state, all emissions were detected from the PPV segments with photoluminescence quantum yields up to 68%. One of the polymers has been used as the active material in a microcavity laser device. The threshold for lasing is 2 muJ/cm(2).
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