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Xiong, W., Tang, S., Murto, P., Zhu, W., Edman, L. & Wang, E. (2019). Combining Benzotriazole and Benzodithiophene Host Units in Host-Guest Polymers for Efficient and Stable Near-Infrared Emission from Light-Emitting Electrochemical Cells. Advanced Optical Materials, 7(15), Article ID 1900280.
Open this publication in new window or tab >>Combining Benzotriazole and Benzodithiophene Host Units in Host-Guest Polymers for Efficient and Stable Near-Infrared Emission from Light-Emitting Electrochemical Cells
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2019 (English)In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 7, no 15, article id 1900280Article in journal (Refereed) Published
Abstract [en]

A set of host-guest copolymers with alternating benzodithiophene and benzotriazole (BTz) derivatives as host units and 4,7-bis(5-bromothiophen-2-yl)-benzo[c][1,2,5]thiadiazole as the minority guest are synthesized, characterized, and evaluated for applications. A light-emitting electrochemical cell (LEC) comprising such a host-guest copolymer delivers fast-response near-infrared (NIR) emission peaked at 723 nm with a high radiance of 169 mu W cm(-2) at a low drive voltage of 3.6 V. The NIR-LEC also features good stability, as the peak NIR output only drops by 8% after 350 h of continuous operation. It is, however, found that the LEC performance is highly sensitive to the detailed chemical structure of the host backbone, and that the addition of electron-donating thiophene bridging units onto the BTz unit is highly positive while the inclusion of fluorine atoms results in a drastically lowered performance, presumably because of the emergence of hydrogen bonding within the active material.

Keywords
conjugated polymers, host-guest copolymers, near-infrared emission light-emitting electrochemical cells
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:umu:diva-162672 (URN)10.1002/adom.201900280 (DOI)000478735800007 ()
Available from: 2019-08-29 Created: 2019-08-29 Last updated: 2019-08-29Bibliographically approved
Tang, S., Murto, P., Wang, J., Larsen, C., Andersson, M. R., Wang, E. & Edman, L. (2019). On the Design of Host-Guest Light-Emitting Electrochemical Cells: Should the Guest be Physically Blended or Chemically Incorporated into the Host for Efficient Emission?. Advanced Optical Materials, 7(18), Article ID 1900451.
Open this publication in new window or tab >>On the Design of Host-Guest Light-Emitting Electrochemical Cells: Should the Guest be Physically Blended or Chemically Incorporated into the Host for Efficient Emission?
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2019 (English)In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 7, no 18, article id 1900451Article in journal (Refereed) Published
Abstract [en]

It has recently been demonstrated that light‐emitting electrochemical cells (LECs) can be designed to deliver strong emission with high efficiency when the charge transport is effectuated by a majority host and the emission is executed by a minority guest. A relevant question is then: should the guest be physically blended with or chemically incorporated into the host? A systematic study is presented that establishes that for near‐infrared‐(NIR‐) emitting LECs based on poly(indacenodithieno[3,2‐b]thiophene) (PIDTT) as the host and 4,7‐bis(4,4‐bis(2‐ethylhexyl)‐4H‐silolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)benzo[c][1,2,5]‐thiadiazole (SBS) as the guest the chemical‐incorporation approach is preferable. The host‐to‐guest energy transfer in LEC devices is highly efficient at a low guest concentration of 0.5%, whereas guest aggregation and ion redistribution during device operation severly inhibits this transfer in the physical‐blend devices. The chemical‐incorporation approach also results in a redshifted emission with a somewhat lowered photoluminescence quantum yield, but the LEC performance is nevertheless very good. Specifically, an NIR‐LEC device comprising a guest‐dilute (0.5 molar%) PIDTT‐SBS copolymer delivers highly stabile operation at a high radiance of 263 µW cm−2 (peak wavelength = 725 nm) and with an external quantum efficiency of 0.214%, which is close to the theoretical limit for this particular emitter and device geometry.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
host-guest copolymers, intramolecular energy transfer, light-emitting electrochemical cells, near-infrared emission
National Category
Materials Engineering Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-164065 (URN)10.1002/adom.201900451 (DOI)000487087400020 ()
Available from: 2019-10-15 Created: 2019-10-15 Last updated: 2019-10-15Bibliographically approved
Tang, S., Murto, P., Wang, J., Larsen, C., Andersson, M. R., Wang, E. & Edman, L. (2019). On the Design of Host-Guest Light-Emitting Electrochemical Cells: Should the Guest be Physically Blended or Chemically Incorporated into the Host for Efficient Emission?. Advanced Optical Materials, 7(18), Article ID 1900451.
Open this publication in new window or tab >>On the Design of Host-Guest Light-Emitting Electrochemical Cells: Should the Guest be Physically Blended or Chemically Incorporated into the Host for Efficient Emission?
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2019 (English)In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 7, no 18, article id 1900451Article in journal (Refereed) Published
Abstract [en]

It has recently been demonstrated that light-emitting electrochemical cells (LECs) can be designed to deliver strong emission with high efficiency when the charge transport is effectuated by a majority host and the emission is executed by a minority guest. A relevant question is then: should the guest be physically blended with or chemically incorporated into the host? A systematic study is presented that establishes that for near-infrared-(NIR-) emitting LECs based on poly(indacenodithieno[3,2-b]thiophene) (PIDTT) as the host and 4,7-bis(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b ']dithiophen-2-yl)benzo[c][1,2,5]-thiadiazole (SBS) as the guest the chemical-incorporation approach is preferable. The host-to-guest energy transfer in LEC devices is highly efficient at a low guest concentration of 0.5%, whereas guest aggregation and ion redistribution during device operation severly inhibits this transfer in the physical-blend devices. The chemical-incorporation approach also results in a redshifted emission with a somewhat lowered photoluminescence quantum yield, but the LEC performance is nevertheless very good. Specifically, an NIR-LEC device comprising a guest-dilute (0.5 molar%) PIDTT-SBS copolymer delivers highly stabile operation at a high radiance of 263 mu W cm(-2) (peak wavelength = 725 nm) and with an external quantum efficiency of 0.214%, which is close to the theoretical limit for this particular emitter and device geometry.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2019
Keywords
host-guest copolymers, intramolecular energy transfer, light-emitting electrochemical cells, near- infrared emission
National Category
Atom and Molecular Physics and Optics Polymer Chemistry
Identifiers
urn:nbn:se:umu:diva-164143 (URN)10.1002/adom.201900451 (DOI)000487087400020 ()
Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17Bibliographically approved
Lindh, E. M., Lundberg, P., Lanz, T. & Edman, L. (2019). Optical analysis of light-emitting electrochemical cells. Scientific Reports, 9, Article ID 10433.
Open this publication in new window or tab >>Optical analysis of light-emitting electrochemical cells
2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 10433Article in journal (Refereed) Published
Abstract [en]

The light-emitting electrochemical cell (LEC) is a contender for emerging applications of light, primarily because it offers low-cost solution fabrication of easily functionalized device architectures. The attractive properties originate in the in-situ formation of electrochemically doped transport regions that enclose an emissive intrinsic region, but the understanding of how this intricate doping structure affects the optical performance of the LEC is largely lacking. We combine angle- and doping-dependent measurements and simulations, and demonstrate that the emission zone in our high-performance LEC is centered at ~30% of the active-layer thickness (dal) from the anode. We further find that the emission intensity and efficiency are undulating with dal, and establish that the first emission maximum at dal ~ 100 nm is largely limited by the lossy coupling of excitons to the doping regions, whereas the most prominent loss channel at the second maximum at dal ~ 300 nm is wave-guided modes.

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
National Category
Nano Technology Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-156092 (URN)10.1038/s41598-019-46860-y (DOI)000475845400037 ()31320711 (PubMedID)2-s2.0-85069470003 (Scopus ID)
Note

Originally included in thesis in manuscript form.

Available from: 2019-02-05 Created: 2019-02-05 Last updated: 2019-08-08Bibliographically approved
Dahlberg, T., Stangner, T., Hanqing, Z., Wiklund, K., Lundberg, P., Edman, L. & Andersson, M. (2018). 3D printed water-soluble scaffolds for rapid production of PDMS micro-fluidic flow chambers. Scientific Reports, 8(1), Article ID 3372.
Open this publication in new window or tab >>3D printed water-soluble scaffolds for rapid production of PDMS micro-fluidic flow chambers
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 3372Article in journal (Refereed) Published
Abstract [en]

We report a novel method for fabrication of three-dimensional (3D) biocompatible micro-fluidic flow chambers in polydimethylsiloxane (PDMS) by 3D-printing water-soluble polyvinyl alcohol (PVA) filaments as master scaffolds. The scaffolds are first embedded in the PDMS and later residue-free dissolved in water leaving an inscription of the scaffolds in the hardened PDMS. We demonstrate the strength of our method using a regular, cheap 3D printer, and evaluate the inscription process and the channels micro-fluidic properties using image analysis and digital holographic microscopy. Furthermore, we provide a protocol that allows for direct printing on coverslips and we show that flow chambers with a channel cross section down to 40 x 300 μm can be realized within 60 min. These flow channels are perfectly transparent, biocompatible and can be used for microscopic applications without further treatment. Our proposed protocols facilitate an easy, fast and adaptable production of micro-fluidic channel designs that are cost-effective, do not require specialized training and can be used for a variety of cell and bacterial assays. To help readers reproduce our micro-fluidic devices, we provide: full preparation protocols, 3D-printing CAD files for channel scaffolds and our custom-made molding device, 3D printer build-plate leveling instructions, and G-code.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Other Materials Engineering Other Engineering and Technologies not elsewhere specified Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-144631 (URN)10.1038/s41598-018-21638-w (DOI)000425500300044 ()
Funder
Swedish Research Council, 2013-5379The Kempe Foundations, JCK-1622
Available from: 2018-02-08 Created: 2018-02-08 Last updated: 2018-08-16Bibliographically approved
Ekeroth, S., Münger, E. P., Boyd, R., Ekspong, J., Wågberg, T., Edman, L., . . . Helmersson, U. (2018). Catalytic nanotruss structures realized by magnetic self-assembly in pulsed plasma. Nano letters (Print), 18(5), 3132-3137
Open this publication in new window or tab >>Catalytic nanotruss structures realized by magnetic self-assembly in pulsed plasma
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2018 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 18, no 5, p. 3132-3137Article in journal (Refereed) Published
Abstract [en]

Tunable nanostructures that feature a high surface area are firmly attached to a conducting substrate and can be fabricated efficiently over significant areas, which are of interest for a wide variety of applications in, for instance, energy storage and catalysis. We present a novel approach to fabricate Fe nanoparticles using a pulsed-plasma process and their subsequent guidance and self-organization into well-defined nanostructures on a substrate of choice by the use of an external magnetic field. A systematic analysis and study of the growth procedure demonstrate that nondesired nanoparticle agglomeration in the plasma phase is hindered by electrostatic repulsion, that a polydisperse nanoparticle distribution is a consequence of the magnetic collection, and that the formation of highly networked nanotruss structures is a direct result of the polydisperse nanoparticle distribution. The nanoparticles in the nanotruss are strongly connected, and their outer surfaces are covered with a 2 nm layer of iron oxide. A 10 μm thick nanotruss structure was grown on a lightweight, flexible and conducting carbon-paper substrate, which enabled the efficient production of H2 gas from water splitting at a low overpotential of 210 mV and at a current density of 10 mA/cm2.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
nanotrusses, nanowires, nanoparticles, iron, electrocatalysis, pulsed sputtering
National Category
Nano Technology
Identifiers
urn:nbn:se:umu:diva-148834 (URN)10.1021/acs.nanolett.8b00718 (DOI)000432093200055 ()29624405 (PubMedID)
Available from: 2018-06-12 Created: 2018-06-12 Last updated: 2018-06-12Bibliographically approved
Jin, X., Sandström, A., Lindh, E. M., Yang, W., Tang, S. & Edman, L. (2018). Challenging conventional wisdom: finding high-performance electrodes for light-emitting electrochemical cells. ACS Applied Materials and Interfaces, 10(39), 33380-33389
Open this publication in new window or tab >>Challenging conventional wisdom: finding high-performance electrodes for light-emitting electrochemical cells
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2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 39, p. 33380-33389Article in journal (Refereed) Published
Abstract [en]

The light-emitting electrochemical cell (LEC) exhibits capacity for efficient charge injection from two air stable electrodes into a single-layer active material, which is commonly interpreted as implying that the LEC operation is independent of the electrode selection. Here, we demonstrate that this is far from the truth and that the electrode selection instead has a strong influence on the LEC performance. We systematically investigate 13 different materials for the positive anode and negative cathode in a common LEC configuration with the conjugated polymer Super Yellow as the electroactive emitter and find that Ca, Mn, Ag, Al, Cu, indium tin oxide (ITO), and Au function as the LEC cathode, whereas ITO and Ni can operate as the LEC anode. Importantly, we demonstrate that the electrochemical stability of the electrode is paramount and that particularly electrochemical oxidation of the anode can prohibit the functional LEC operation. We finally report that it appears preferable to design the device so that the heights of the injection barriers at the two electrode/active material interfaces are balanced in order to mitigate electrode-induced quenching of the light emission. As such, this study has expanded the set of air-stable electrode materials available for functional LEC operation and also established a procedure for the evaluation and design of future efficient electrode materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
air-stable electrode, injection barrier, light-emitting electrochemical cell, electrochemical stability, reflectance
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-152982 (URN)10.1021/acsami.8b13036 (DOI)000446919800049 ()30199215 (PubMedID)
Funder
Swedish Foundation for Strategic Research Swedish Research CouncilSwedish Energy AgencyThe Kempe Foundations
Available from: 2018-11-01 Created: 2018-11-01 Last updated: 2018-11-01Bibliographically approved
Murto, P., Tang, S., Larsen, C., Xu, X., Sandström, A., Pietarinen, J., . . . Edman, L. (2018). Incorporation of Designed Donor-Acceptor-Donor Segments in a Host Polymer for Strong Near-Infrared Emission from a Large-Area Light-Emitting Electrochemical Cell. ACS Applied Energy Materials, 1(4), 1753-1761
Open this publication in new window or tab >>Incorporation of Designed Donor-Acceptor-Donor Segments in a Host Polymer for Strong Near-Infrared Emission from a Large-Area Light-Emitting Electrochemical Cell
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2018 (English)In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 4, p. 1753-1761Article in journal (Refereed) Published
Abstract [en]

Cost-efficient thin-film devices that emit in the near-infrared (NIR) range promise a wide range of important applications. Here, the synthesis and NIR application of a series of copolymers comprising poly[indacenodithieno[3,2-b]thiophene-2,8-diyl] (PIDTT) as the host and different donor–acceptor–donor (DAD) segments as the guest are reported. We find that a key design criterion for efficient solid-state host-to-guest energy transfer is that the DAD conformation is compatible with the conformation of the host. Such host–guest copolymers are evaluated as the emitter in light-emitting electrochemical cells (LECs) and organic light-emitting diodes, and the best performance is invariably attained from the LEC devices because of the observed balanced electrochemical doping that alleviates issues with a noncentered emission zone. An LEC device comprising a host–guest copolymer with 4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene as the donor and benzo[c][1,2,5]thiadiazole as the acceptor delivers an impressive near-infrared (NIR) performance in the form of a high radiance of 1458 μW/cm2 at a peak wavelength of 725 nm when driven by a current density of 500 mA/cm2, a second-fast turn-on, and a good stress stability as manifested in a constant radiance output during 3 days of uninterrupted operation. The high-molecular-weight copolymer features excellent processability, and the potential for low-cost and scalable NIR applications is verified through a spray-coating fabrication of a >40 cm2 large-area device, which emits intense and uniform NIR light at a low drive voltage of 4.5 V.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
near-infrared, NIR, large-area device, light-emitting electrochemical cell, LEC, copolymer, solution processing
Identifiers
urn:nbn:se:umu:diva-157352 (URN)10.1021/acsaem.8b00283 (DOI)000458705400044 ()
Funder
Swedish Foundation for Strategic Research Swedish Research CouncilSwedish Energy AgencySwedish Research Council Formas
Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-03-15Bibliographically approved
Murto, P., Tang, S., Larsen, C., Xu, X., Sandström, A., Pietarinen, J., . . . Edman, L. (2018). Incorporation of Designed Donor-Acceptor-Donor Segments in a Host Polymer for Strong Near-Infrared Emission from a Large-Area Light-Emitting Electrochemical Cell. ACS Applied Energy Materials, 1(4), 1753-1761
Open this publication in new window or tab >>Incorporation of Designed Donor-Acceptor-Donor Segments in a Host Polymer for Strong Near-Infrared Emission from a Large-Area Light-Emitting Electrochemical Cell
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2018 (English)In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 4, p. 1753-1761Article in journal (Refereed) Published
Abstract [en]

Cost-efficient thin-film devices that emit in the near infrared (NIR) range promise a wide range of important applications. Here, the synthesis and NIR application of a series of copolymers comprising poly[indacenodithieno[3,2-b]thiophene-2,8-diyl] (PIDTT) as the host and different donor acceptor donor (DAD) segments as the guest are reported. We find that a key design criterion for efficient solid-state host-to-guest energy transfer is that the DAD conformation is compatible with the conformation of the host. Such host guest copolymers are evaluated as the emitter in light-emitting electrochemical cells (LECs) and organic light-emitting diodes, and the best performance is invariably attained from the LEC devices because of the observed balanced electrochemical doping that alleviates issues with a noncentered emission zone. An LEC device comprising a host guest copolymer with 4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene as the donor and benzo[c][1,2,5]thiadiazole as the acceptor delivers an impressive near-infrared (NIR) performance in the form of a high radiance of 1458 mu W/cm(2) at a peak wavelength of 725 nm when driven by a current density of 500 mA/cm(2), a second-fast turn-on, and a good stress stability as manifested in a constant radiance output during 3 days of uninterrupted operation. The high-molecular-weight copolymer features excellent processability, and the potential for low-cost and scalable NIR applications is verified through a spray-coating fabrication of a >40 cm(2) large-area device, which emits intense and uniform NIR light at a low drive voltage of 4.5 V.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
near-infrared, NIR, large-area device, light-emitting electrochemical cell, LEC, copolymer, solution processing
National Category
Polymer Chemistry Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-156904 (URN)10.1021/acsaem.8b00283 (DOI)000458705400044 ()
Available from: 2019-04-16 Created: 2019-04-16 Last updated: 2019-04-16Bibliographically approved
Mindemark, J., Tang, S., Li, H. & Edman, L. (2018). Ion Transport beyond the Polyether Paradigm: Introducing Oligocarbonate Ion Transporters for Efficient Light-Emitting Electrochemical Cells. Advanced Functional Materials, 28(32), Article ID 1801295.
Open this publication in new window or tab >>Ion Transport beyond the Polyether Paradigm: Introducing Oligocarbonate Ion Transporters for Efficient Light-Emitting Electrochemical Cells
2018 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 32, article id 1801295Article in journal (Refereed) Published
Abstract [en]

The light-emitting electrochemical cell (LEC) is fundamentally dependent on mobile ions for its operation. In polymer LECs, the mobile ions are commonly provided by dissolving a salt in an ion transporter, with the latter almost invariably being an ether-based compound. Here, the synthesis, characterization, and application of a new class of carbonate-based ion transporters are reported. A polymer LEC, comprising a star-branched oligocarbonate endowed with aliphatic side groups as the ion transporter, features a current efficacy of 13.8 cd A(-1) at a luminance of 1060 cd m(-2), which is a record-high efficiency/luminance combination for a singlet-emitting LEC. It is further established that the design principles of a high-performance carbonate ion transporter constitute the selection of an oligomeric structure over a corresponding polymeric structure and the endowment of the oligomer with functional side chains to render it compatible with the polymeric emitter.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
light emission, organic electronics, phase separation, polycarbonates, polymer electrolytes
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-151048 (URN)10.1002/adfm.201801295 (DOI)000440810500004 ()
Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-05Bibliographically approved
Projects
Organisk elektronik - nanodesign för funktionella applikationer [P34145-2_Energi]; Umeå UniversityThe light-emitting electrochemical cell: Developing rational design principles for efficient, bright and green operation [2017-04380_VR]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2495-7037

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