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Matyba, Piotr
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Chen, C., Tao, Z., Carr, A., Matyba, P., Szilvasi, T., Emmerich, S., . . . Murnane, M. (2017). Distinguishing attosecond electron-electron scattering and screening in transition metals. Proceedings of the National Academy of Sciences of the United States of America, 114(27), E5300-E5307
Öppna denna publikation i ny flik eller fönster >>Distinguishing attosecond electron-electron scattering and screening in transition metals
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2017 (Engelska)Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, nr 27, s. E5300-E5307Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Electron-electron interactions are the fastest processes in materials, occurring on femtosecond to attosecond timescales, depending on the electronic band structure of the material and the excitation energy. Such interactions can play a dominant role in light-induced processes such as nano-enhanced plasmonics and catalysis, light harvesting, or phase transitions. However, to date it has not been possible to experimentally distinguish fundamental electron interactions such as scattering and screening. Here, we use sequences of attosecond pulses to directly measure electron-electron interactions in different bands of different materials with both simple and complex Fermi surfaces. By extracting the time delays associated with photoemission we show that the lifetime of photoelectrons from the d band of Cu are longer by similar to 100 as compared with those from the same band of Ni. We attribute this to the enhanced electron-electron scattering in the unfilled d band of Ni. Using theoretical modeling, we can extract the contributions of electron-electron scattering and screening in different bands of different materials with both simple and complex Fermi surfaces. Our results also show that screening influences high-energy photoelectrons (approximate to 20 eV) significantly less than low-energy photoelectrons. As a result, high-energy photoelectrons can serve as a direct probe of spin-dependent electron-electron scattering by neglecting screening. This can then be applied to quantifying the contribution of electron interactions and screening to low-energy excitations near the Fermi level. The information derived here provides valuable and unique information for a host of quantum materials.

Ort, förlag, år, upplaga, sidor
National Academy of Sciences, 2017
Nyckelord
attosecond science, high harmonic generation, ARPES, electron-electron interactions
Nationell ämneskategori
Den kondenserade materiens fysik Atom- och molekylfysik och optik
Identifikatorer
urn:nbn:se:umu:diva-138544 (URN)10.1073/pnas.1706466114 (DOI)000404576100006 ()28630331 (PubMedID)
Tillgänglig från: 2017-09-25 Skapad: 2017-09-25 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Bergues, B., Rivas, D. E., Weidman, M., Muschet, A., Helml, W., Guggenmos, A., . . . Veisz, L. (2017). Towards Attosecond XUV-Pump XUV-Probe Measurements in the 100-eV Region. In: 2017 Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC): . Paper presented at Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), JUN 25-29, 2017, Munich, GERMANY. IEEE
Öppna denna publikation i ny flik eller fönster >>Towards Attosecond XUV-Pump XUV-Probe Measurements in the 100-eV Region
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2017 (Engelska)Ingår i: 2017 Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), IEEE, 2017Konferensbidrag, Muntlig presentation med publicerat abstract (Refereegranskat)
Ort, förlag, år, upplaga, sidor
IEEE, 2017
Nationell ämneskategori
Atom- och molekylfysik och optik
Identifikatorer
urn:nbn:se:umu:diva-152152 (URN)10.1109/CLEOE-EQEC.2017.8086792 (DOI)000432564600551 ()978-1-5090-6736-7 (ISBN)
Konferens
Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), JUN 25-29, 2017, Munich, GERMANY
Tillgänglig från: 2018-10-01 Skapad: 2018-10-01 Senast uppdaterad: 2018-10-01Bibliografiskt granskad
Matyba, P. (2011). Polymer light-emitting electrochemical cells: Utilizing doping for generation of light. (Doctoral dissertation). Umeå: Department of Physics, Umeå University
Öppna denna publikation i ny flik eller fönster >>Polymer light-emitting electrochemical cells: Utilizing doping for generation of light
2011 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

    The current implementation of conjugated polymers (“conducting plastics”) in a wide range of devices promises to bring the vision of a new generation of flexible, efficient and low-cost applications to reality. Plastic lightemitting devices in the form of polymer light-emitting diodes (PLEDs) are projected to be particularly close to the market in applications such as large area and conformable illumination panels and high-performance thin displays. However, two notable drawbacks of PLEDs are that they depend on vacuum deposition of a reactive metal for the negative electrode and that the active material must be extremely thin and uniform in thickness. As a consequence, PLEDs cannot be expected to allow for a low-cost continuous production using a roll-to-roll coating and/or printing process.

This thesis focuses on an alternative to the PLED: A light-emitting electrochemical cell (LEC). LECs comprise a mixture of a conjugated polymer and a solid-state electrolyte as the active material positioned between two electrodes. The existence of mobile ions in the active material allows for a number of interesting attributes, both from a fundamental science and an application perspective. Importantly, the ions and the related unique operation of LECs make these devices apt for the utilization of low-cost roll-to-roll fabrication of the entire device as the electrode materials can be air stable and solution-processible and the requirement on the thickness of the active material is much less stringent than in PLEDs.

   The herein presented “basic science” studies primarily focus on the operation of LECs. It is for instance firmly established that a light-emitting p-n junction can form in-situ in a LEC device during the application of a voltage. This dynamic p-n junction exhibits some similarities, but also distinct differences, in comparison to the static p-n junctions that are exploited in crystalline inorganic semiconductor devices. We have also systematically explored the role that the constituent materials (ions, conjugated polymer, ionic solvent, and electrode material) can have on the performance of LECs, and two of the more important findings are that the concentration of ions can influence the doping structure in a motivated fashion and that it is critically important to consider the electrochemical stability window of the constituent materials in order to attain stable device operation.

   With this knowledge at hand, we have executed a number of more “applied science” studies, where we have used the acquired information from the basic-science studies for the rational design of improved devices. We have demonstrated LEC devices with significantly improved device performance, as exemplified by an orange-red device that emitted significant light (> 100 cd/m2) for more than one month of uninterrupted operation, and a yellow-green device that emitted significant light for 25 days at a low voltage of 4 V and at relatively high efficiency (6 lm/W). Finally, we have conceptualized and realized a solely solution-processed and metal-free LEC comprising graphene as the negative electrode and the conducting polymer PEDOT-PSS as the positive electrode. This type of devices represents a paradigm shift in the field of solid-state lighting as they demonstrate that it is possible to fabricate an entire light-emitting device from solution-processible and “green” carbon-based materials in a process that is akin to printing.

Ort, förlag, år, upplaga, sidor
Umeå: Department of Physics, Umeå University, 2011. s. 67
Identifikatorer
urn:nbn:se:umu:diva-38953 (URN)978-91-7459-124-8 (ISBN)
Disputation
2011-02-04, Mit-huset, MA 121, Umeå universitet, Umeå, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2011-01-13 Skapad: 2011-01-11 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Bychkov, V., Matyba, P., Akkerman, V., Modestov, M., Valiev, D., Brodin, G., . . . Edman, L. (2011). Speedup of doping fronts in organic semiconductors through plasma instability. Physical Review Letters, 107(1), 016103-016107
Öppna denna publikation i ny flik eller fönster >>Speedup of doping fronts in organic semiconductors through plasma instability
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2011 (Engelska)Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, nr 1, s. 016103-016107Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The dynamics of doping transformation fronts in organic semiconductor plasma is studied for application in light-emitting electrochemical cells. We show that new fundamental effects of the plasma dynamics can significantly improve the device performance. We obtain an electrodynamic instability, which distorts the doping fronts and increases the transformation rate considerably. We explain the physical mechanism of the instability, develop theory, provide experimental evidence, perform numerical simulations, and demonstrate how the instability strength may be amplified technologically. The electrodynamic plasma instability obtained also shows interesting similarity to the hydrodynamic Darrieus-Landau instability in combustion, laser ablation, and astrophysics.

Nyckelord
Semiconductor materials in electrochemistry, Polymers; organic compounds
Nationell ämneskategori
Fysik
Identifikatorer
urn:nbn:se:umu:diva-45433 (URN)10.1103/PhysRevLett.107.016103 (DOI)
Tillgänglig från: 2011-07-04 Skapad: 2011-07-04 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
van Reenen, S., Matyba, P., Dzwilewski, A., Rene A. J., J., Edman, L. & Martijn, K. (2010). A unifying model for the operation of light-emitting electrochemical cells. Journal of the American Chemical Society, 132(39), 13776-13781
Öppna denna publikation i ny flik eller fönster >>A unifying model for the operation of light-emitting electrochemical cells
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2010 (Engelska)Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, nr 39, s. 13776-13781Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The application of doping in semiconductors plays a major role in the high performances achieved to date in inorganic devices. In contrast, doping has yet to make such an impact in organic electronics. One organic device that does make extensive use of doping is the light-emitting electrochemical cell (LEC), where the presence of mobile ions enables dynamic doping, which enhances carrier injection and facilitates relatively large current densities. The mechanism and effects of doping in LECs are, however, still far from being fully understood, as evidenced by the existence of two competing models that seem physically distinct: the electrochemical doping model and the electrodynamic model. Both models are supported by experimental data and numerical modeling. Here, we show that these models are essentially limits of one master model, separated by different rates of carrier injection. For ohmic nonlimited injection, a dynamic p−n junction is formed, which is absent in injection-limited devices. This unification is demonstrated by both numerical calculations and measured surface potentials as well as light emission and doping profiles in operational devices. An analytical analysis yields an upper limit for the ratio of drift and diffusion currents, having major consequences on the maximum current density through this type of device.

Ort, förlag, år, upplaga, sidor
American Chemical Society, 2010
Identifikatorer
urn:nbn:se:umu:diva-38943 (URN)10.1021/ja1045555 (DOI)000282864100048 ()
Tillgänglig från: 2011-01-11 Skapad: 2011-01-11 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Dzwilewski, A., Matyba, P. & Edman, L. (2010). Facile fabrication of efficient organic CMOS circuits. Journal of Physical Chemistry B, 114(1), 135-140
Öppna denna publikation i ny flik eller fönster >>Facile fabrication of efficient organic CMOS circuits
2010 (Engelska)Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, nr 1, s. 135-140Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Organic electronic circuits based on a combination of n- and p-type transistors (so-called CMOS circuits) are attractive, since they promise the realization of a manifold of versatile and low-cost electronic devices. Here, we report a novel photoinduced transformation method, which allows for a particularly straightforward fabrication of highly functional organic CMOS circuits. A solution-deposited single-layer film, comprising a mixture of the n-type semiconductor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and the p-type semiconductor poly-3-hexylthiophene (P3HT) in a 3:1 mass ratio, was utilized as the common active material in an array of transistors. Selected film areas were exposed to laser light, with the result that the irradiated PCBM monomers were photochemically transformed into a low-solubility and high-mobility dimeric state. Thereafter, the entire film was developed via immersion into a developer solution, which selectively removed the nonexposed, and monomeric, PCBM component. The end result was that the transistors in the exposed film areas are n-type, as dimeric PCBM is the majority component in the active material, while the transistors in the nonexposed film areas are p-type, as P3HT is the sole remaining material. We demonstrate the merit of the method by utilizing the resulting combination of n-type and p-type transistors for the realization of CMOS inverters with a high gain of ∼35.

Ort, förlag, år, upplaga, sidor
American Chemical Society (ACS), 2010
Nationell ämneskategori
Fysikalisk kemi
Identifikatorer
urn:nbn:se:umu:diva-30613 (URN)10.1021/jp909216a (DOI)000273404500018 ()20055524 (PubMedID)
Tillgänglig från: 2010-01-08 Skapad: 2010-01-08 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Matyba, P., Yamaguchi, H., Eda, G., Chhowalla, M., Edman, L. & Robinson, N. D. (2010). Graphene and mobile ions: the key to all-plastic, solution-processed light-emitting devices. ACS Nano, 4(2), 637-642
Öppna denna publikation i ny flik eller fönster >>Graphene and mobile ions: the key to all-plastic, solution-processed light-emitting devices
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2010 (Engelska)Ingår i: ACS Nano, ISSN 1936-0851, Vol. 4, nr 2, s. 637-642Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The emerging field of “organic” or “plastic” electronics has brought low-voltage, ultrathin, and energy-efficient lighting and displays to market as organic light-emitting diode (OLED) televisions and displays in cameras and mobile phones. Despite using carbon-based materials as the light-emitting layer, previous efficient organic electronic light-emitting devices have required at least one metal electrode. Here, we utilize chemically derived graphene for the transparent cathode in an all-plastic sandwich-structure device, similar to an OLED, called a light-emitting electrochemical cell (LEC). Using a screen-printable conducting polymer as a partially transparent anode and a micrometer-thick active layer solution-deposited from a blend of a light-emitting polymer and a polymer electrolyte, we demonstrate a light-emitting device based solely on solution-processable carbon-based materials. Our results demonstrate that low-voltage, inexpensive, and efficient light-emitting devices can be made without using metals. In other words, electronics can truly be “organic”.

Ort, förlag, år, upplaga, sidor
American Chemical Society Publications, 2010
Nyckelord
graphene, light-emitting device, polymer, light-emitting, electrochemical cell, electroluminescence
Identifikatorer
urn:nbn:se:umu:diva-35840 (URN)10.1021/nn9018569 (DOI)000274635800009 ()
Tillgänglig från: 2010-09-07 Skapad: 2010-09-07 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Modestov, M., Bychkov, V., Brodin, G., Valiev, D., Marklund, M., Matyba, P. & Edman, L. (2010). Model of the electrochemical conversion of an undoped organic semiconductor film to a doped conductor film.. Physical Review B. Condensed Matter and Materials Physics, 81(8), 081203(R)
Öppna denna publikation i ny flik eller fönster >>Model of the electrochemical conversion of an undoped organic semiconductor film to a doped conductor film.
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2010 (Engelska)Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, nr 8, s. 081203(R)-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We develop a model describing the electrochemical conversion of an organic semiconductor (specifically, the active material in a light-emitting electrochemical cell) from the undoped nonconducting state to the doped conducting state. The model, an extended Nernst-Planck-Poisson model, takes into account both strongly concentration-dependent mobility and diffusion for the electronic charge carriers and the Nernst equation in the doped conducting regions. The standard Nernst-Planck-Poisson model is shown to fail in its description of the properties of the doping front. Solving our extended model numerically, we demonstrate that doping front progression in light-emitting electrochemical cells can be accurately described.

Nyckelord
Theory of electronic transport, Scattering mechanisms, Polymers and organic materials in electrochemistry
Nationell ämneskategori
Fysik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:umu:diva-32325 (URN)10.1103/PhysRevB.81.081203 (DOI)000275053300008 ()
Tillgänglig från: 2010-03-09 Skapad: 2010-03-09 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Sandström, A., Matyba, P., Inganäs, O. & Edman, L. (2010). Separating ion and and electron transport: the bi-layer light-emitting electrochemical cell. Journal of the American Chemical Society, 132(19), 6646-6647
Öppna denna publikation i ny flik eller fönster >>Separating ion and and electron transport: the bi-layer light-emitting electrochemical cell
2010 (Engelska)Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, nr 19, s. 6646-6647Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

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.

Ort, förlag, år, upplaga, sidor
ACS Publications, 2010
Identifikatorer
urn:nbn:se:umu:diva-35843 (URN)10.1021/ja102038e (DOI)000277721500017 ()
Tillgänglig från: 2010-09-07 Skapad: 2010-09-07 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Sandström, A., Matyba, P. & Edman, L. (2010). Yellow-green light-emitting electrochemical cells with long lifetime and high efficiency. Applied Physics Letters, 96(5), 053303
Öppna denna publikation i ny flik eller fönster >>Yellow-green light-emitting electrochemical cells with long lifetime and high efficiency
2010 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 96, nr 5, s. 053303-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

 We show that the electrochemical stability window of the constituent components in light-emitting electrochemical cells (LECs), e.g., the electrolyte, should be considered in order to minimize undesired side reactions. By designing and operating LECs in accordance with straightforward principles, we demonstrate sandwich cells that turn on fast at room temperature (<2 s), and which emit significant yellow-green light (>100 cd/m2) during 25 days of uninterrupted operation at low voltage (<4 V) and high power conversion efficacy ~6 lm/W. We further demonstrate that it is possible to attain balanced p- and n-type doping and a centered p-n junction in such planar LECs based on the conjugated polymer “superyellow.”

Identifikatorer
urn:nbn:se:umu:diva-35841 (URN)10.1063/1.3299018 (DOI)000274319500102 ()
Tillgänglig från: 2010-09-07 Skapad: 2010-09-07 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
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