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Lanz, Thomas
Publications (5 of 5) Show all publications
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
Lindh, E. M., Lundberg, P., Lanz, T., Mindemark, J. & Edman, L. (2018). The Weak Microcavity as an Enabler for Bright and Fault-tolerant Light-emitting Electrochemical Cells. Scientific Reports, 8, Article ID 6970.
Open this publication in new window or tab >>The Weak Microcavity as an Enabler for Bright and Fault-tolerant Light-emitting Electrochemical Cells
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 6970Article in journal (Refereed) Published
Abstract [en]

The light-emitting electrochemical cell (LEC) is functional at substantial active-layer thickness, and is as such heralded for being fit for low-cost and fault-tolerant solution-based fabrication. We report here that this statement should be moderated, and that in order to obtain a strong luminous output, it is fundamentally important to fabricate LEC devices with a designed thickness of the active layer. By systematic experimentation and simulation, we demonstrate that weak optical microcavity effects are prominent in a common LEC system, and that the luminance and efficiency, as well as the emission color and the angular intensity, vary in a periodic manner with the active-layer thickness. Importantly, we demonstrate that high-performance light-emission can be attained from LEC devices with a significant active-layer thickness of 300 nm, which implies that low-cost solution-processed LECs are indeed a realistic option, provided that the device structure has been appropriately designed from an optical perspective.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-147802 (URN)10.1038/s41598-018-25287-x (DOI)000431291500022 ()29725061 (PubMedID)
Note

Publisher Correction: M. Lindh, P. Lundberg, T. Lanz, J. Mindemark, L. Edman. The Weak Microcavity as an Enabler for Bright and Fault-tolerant Light-emitting Electrochemical Cells. Scientific Reports. 2018;8 DOI: 10.1038/s41598-018-26760-3

Available from: 2018-05-22 Created: 2018-05-22 Last updated: 2019-02-05Bibliographically approved
Tang, S., Sandström, A., Lundberg, P., Lanz, T., Larsen, C., van Reenen, S., . . . Edman, L. (2017). Design rules for light-emitting electrochemical cells delivering bright luminance at 27.5 percent external quantum efficiency. Nature Communications, 8, Article ID 1190.
Open this publication in new window or tab >>Design rules for light-emitting electrochemical cells delivering bright luminance at 27.5 percent external quantum efficiency
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2017 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, article id 1190Article in journal (Refereed) Published
Abstract [en]

The light-emitting electrochemical cell promises cost-efficient, large-area emissive applications, as its characteristic in-situ doping enables use of air-stabile electrodes and a solution-processed single-layer active material. However, mutual exclusion of high efficiency and high brightness has proven a seemingly fundamental problem. Here we present a generic approach that overcomes this critical issue, and report on devices equipped with air-stabile electrodes and outcoupling structure that deliver a record-high efficiency of 99.2 cd A(-1) at a bright luminance of 1910 cd m(-2). This device significantly outperforms the corresponding optimized organic light-emitting diode despite the latter employing calcium as the cathode. The key to this achievement is the design of the host-guest active material, in which tailored traps suppress exciton diffusion and quenching in the central recombination zone, allowing efficient triplet emission. Simultaneously, the traps do not significantly hamper electron and hole transport, as essentially all traps in the transport regions are filled by doping.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Other Physics Topics Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-141807 (URN)10.1038/s41467-017-01339-0 (DOI)000413894100012 ()29085078 (PubMedID)
Available from: 2017-11-27 Created: 2017-11-27 Last updated: 2018-06-09Bibliographically approved
Lanz, T., Lindh, E. M. & Edman, L. (2017). On the asymmetric evolution of the optical properties of a conjugated polymer during electrochemical p- and n-type doping. Journal of Materials Chemistry C, 5(19), 4706-4715
Open this publication in new window or tab >>On the asymmetric evolution of the optical properties of a conjugated polymer during electrochemical p- and n-type doping
2017 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 19, p. 4706-4715Article in journal (Refereed) Published
Abstract [en]

We report on the in situ measured evolution of the spectral complex refractive index of a prototypical conjugated polymer, a phenyl-substituted poly (para-phenylenevinylene) copolymer (Ph-PPV, “Super Yellow”), during electrochemical p- and n-type doping. We find that the real part of the refractive index is lowered in a significant and continuous fashion over essentially the entire visible range with doping, as exemplified by a drop in the peak value at ∼480 nm from 2.1 for pristine Ph-PPV to 1.8 at a p-type doping concentration of 0.2 dopants per repeat unit and an n-type doping concentration of 0.6 dopants per repeat unit. The imaginary part features a concomitant distinct bleaching of the high-energy π–π* transition and the emergence of a low-energy polaron band. Interestingly, we observe that the optical response of Ph-PPV to p-type and n-type doping is highly asymmetric, with the former resulting in much stronger changes and a distinct blue-shift of all optical transitions. We tentatively attribute this difference in response to larger effective size of the p-type polaron compared to the n-type polaron. We anticipate that the presented results should be of value for the rational design of emerging optical devices that utilize the doping capacity of conjugated polymers.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Materials Chemistry Physical Sciences
Identifiers
urn:nbn:se:umu:diva-135968 (URN)10.1039/c7tc01022b (DOI)000401712700013 ()
Available from: 2017-06-27 Created: 2017-06-27 Last updated: 2019-02-05Bibliographically approved
Lanz, T., Sandström, A., Tang, S., Chabrecek, P., Sonderegger, U. & Edman, L. (2016). A light–emission textile device: conformal spray-sintering of a woven fabric electrode. Flexible and Printed Electronics, 1(2), Article ID 025004.
Open this publication in new window or tab >>A light–emission textile device: conformal spray-sintering of a woven fabric electrode
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2016 (English)In: Flexible and Printed Electronics, ISSN 2058-8585, Vol. 1, no 2, article id 025004Article in journal (Refereed) Published
Abstract [en]

We report on the realization of an ultra-flexible, light-weight and large-area emissive textile device. The anode and active material of a light-emitting electrochemical cell (LEC) were deposited by conformal spray-coating of a transparent fabric-based electrode, comprising a weave of fine Ag-coated Cu wires and poly(ethylene naphthalene) monofilament fibers embedded in a polyurethane matrix. The yellow-emitting textile featured low turn-on voltage (5 V), high maximum brightness (>4000 cd m−2), good efficiency (3.4 cd A−1), and reasonable lifetime (180 h at >100 cd m−2). Uniform emission to the eye was attained from thin and highly flexible textiles featuring a large emission area of 42 cm2, without resorting to planarization of the partially wavy-shaped (valley-to-peak height = 2.7 μm) fabric electrode. The key enabling factors for the functional emissive textile are the characteristic in situ electrochemical doping of LEC devices, the 'dry' spray-sintering deposition of the active material, and the attractive mechanical, electronic and optical properties of the fabric-based electrode.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2016
National Category
Textile, Rubber and Polymeric Materials Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:umu:diva-124284 (URN)10.1088/2058-8585/1/2/025004 (DOI)000399176000006 ()
Available from: 2016-08-01 Created: 2016-08-01 Last updated: 2018-06-07Bibliographically approved
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