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Spraying Light: Ambient-Air Fabrication of Large-Area Emissive Devices on Complex-Shaped Surfaces
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
2014 (Engelska)Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 26, nr 29, s. 4975-4980Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Light-emitting electrochemical cells, featuring uniform and efficient light emission over areas of 200 cm(2), are fabricated under ambient air with a for-the-purpose developed "spray-sintering" process. This fault-tolerant fabrication technique can also produce multicolored emission patterns via sequential deposition of different inks based on identical solvents. Significantly, additive spray-sintering using a mobile airbrush allows a straightforward addition of emissive function onto a wide variety of complex-shaped surfaces, as exemplified by the realization of a light-emitting kitchenware fork.

Ort, förlag, år, upplaga, sidor
2014. Vol. 26, nr 29, s. 4975-4980
Nyckelord [en]
large-area light emission, complex surfaces, solution-based processing, ambient fabrication, light-emitting electrochemical cell
Nationell ämneskategori
Atom- och molekylfysik och optik
Identifikatorer
URN: urn:nbn:se:umu:diva-93224DOI: 10.1002/adma.201401286ISI: 000340500700011OAI: oai:DiVA.org:umu-93224DiVA, id: diva2:774279
Ingår i projekt
Lysande tapeter på rulle, Stiftelsen för strategisk forskning (SSF)Tillgänglig från: 2014-12-22 Skapad: 2014-09-15 Senast uppdaterad: 2019-12-18Bibliografiskt granskad
Ingår i avhandling
1. Functional and Flexible Light-Emitting Electrochemical Cells
Öppna denna publikation i ny flik eller fönster >>Functional and Flexible Light-Emitting Electrochemical Cells
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The introduction of artificial illumination has brought extensive benefits to mankind, and during the last years we have seen a tremendous progress in this field with the introduction of the energy-efficient light-emitting diode (LED) and the high-contrast organic LED display. These high-end technologies are, however, produced using costly and complex processes, and it is anticipated that the next big thing in the field will be the advent of a low-cost and “green” illumination technology, which can be fabricated in a cost- and material-efficient manner using non-toxic and abundant raw materials, and which features attractive form factors such as flexibility, robustness and light-weight. The light-emitting electrochemical cell (LEC) is a newly invented illumination technology, and in this thesis we present results that imply that it can turn the above vision into reality.

The thin-film LEC comprises an active material sandwiched between a cathode and an anode as its key constituent parts. With the aid of a handheld air-brush, we show that functional large-area LECs can be fabricated by simply spraying three layers of solution -- forming the anode, active material, and cathode -- on top of a substrate. We also demonstrate that such “spray-sintered” LECs can feature multicolored emission patterns, and be fabricated directly on complex-shaped surfaces, with one notable example being the realization of a light-emission fork!

Almost all LECs up-to-date have been fabricated on glass substrates, but for a flexible and light-weight emissive device, it is obviously relevant to identify more appropriate substrate materials. For this end, we show that it is possible to spray-coat the entire LEC directly on conventional copy paper, and that such paper-LECs feature uniform light-emission even under heavy bending and flexing.

We have further looked into the fundamental aspects of the LEC operation and demonstrated that the in-situ doping formation, which is a characteristic and heralded feature of LECs, can bring problems in the form of doping-induced self-absorption. By quantitatively analyzing this phenomenon, we provided straightforward guidelines on how future efficiency-optimized LEC devices should be designed.

The in-situ doping formation process brings the important advantage that LECs can be fabricated from solely air-stabile materials, but during light emission the device needs to be protected from the ambient air. We have therefore developed a functional glass/epoxy encapsulation procedure for the attainment of LEC devices that feature a record-long ambient-air operational lifetime of 5600 h. For the light-emission device of the future, it is however critical that the encapsulation is flexible, and in our last study, we show that the use of multi-layer barrier can result in high-performance flexible LECs.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå University, 2015. s. 57
Nyckelord
all-ambient fabrication, ambient-air lifetime, encapsulation, flexible, light-emitting electrochemical cells, light-emitting paper
Nationell ämneskategori
Nanoteknik Annan fysik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:umu:diva-102400 (URN)978-91-7601-257-4 (ISBN)
Disputation
2015-05-22, N300, Naturvetarhuset, Umeå University, Umeå, 10:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2015-04-30 Skapad: 2015-04-23 Senast uppdaterad: 2018-06-07Bibliografiskt granskad
2. Structure and morphology control of organic semiconductors for functional optoelectronic applications
Öppna denna publikation i ny flik eller fönster >>Structure and morphology control of organic semiconductors for functional optoelectronic applications
2019 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The functionality and application of organic semiconductors are largely dependent on their constituent structure and morphology. This thesis presents a number of functional and novel approaches for the control and tuning of structural and morphological features of a variety of organic semiconductor materials, and also demonstrates that these approaches can be utilized for improved device operation of field-effect transistors, organic solar cells and light-emitting electrochemical cells.

The fullerene family is a particular group of closed-cage organic semiconductors, which can be photochemically coupled into larger dimeric or polymeric structures through the excitation of the fullerene molecules by light emission. In Paper I, we perform a detailed experimental and analytical investigation, which demonstrates that this photochemical monomer-to-dimer transformation requires that both constituent fullerene molecules are photoexcited. The direct consequence is that the initial probability for the photochemical transformation is dependent on the square of the light-emission intensity.

The photochemical coupling of fullerene molecules commonly results in a distinctly lowered solubility in common hydrophobic solvents, which can be utilized for the direct patterning of fullerene films by resist-free lithography. In Paper II, we utilize this patterning opportunity for the fabrication of one-dimensional fullerene nano-stripes using two-beam laser interference lithography. A desired high contrast between the patterned and non-patterned fullerene regions is facilitated by the non-linear response of the photochemical transformation process, as predicted by the findings in Paper I. The patterned fullerene nano-stripes were utilized as the active material in field-effect transistors, which featured high electron mobility and large on-off ratio.

This patterning was in Paper III extended into easy tunable two-dimensional fullerene structures by the design and development of an exposure setup, essentially comprising a laser and a spatial light modulator featuring >8 millions of independently controlled mirrors. With this approach, we could fabricate well-defined fullerene microdots over a several square-millimeter sized area, which was utilized as an internal out-coupling layer in a light-emitting electrochemical cell with significantly enhanced light output.

Paper IV reports on the development of a new “spray-sintering” method for the cost-efficient solution-based deposition of the active material in light-emitting electrochemical cells. This carefully designed approach effectively resolves the issue with phase separation between the hydrophobic organic semiconductor and the hydrophilic electrolyte that results in a sub-par LEC performance, and also allows for the direct fabrication of LEC devices onto complex surfaces, including a stainless-steel fork.

Paper V finally reports on the design and synthesis of a soluble small molecule, featuring a donor-acceptor-donor configuration. It acts as the donor when combined with a soluble fullerene acceptor in the active material of organic solar cells, and such devices with optimized donor/acceptor nanomorphology feature a high open-circuit voltage of ~1.0 V during solar illumination.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå University, 2019. s. 65
Nyckelord
Organic electronics, organic photonics, patterning, fullerene, polymerization, dimerization, spray-deposition, morphology, small molecule donor, high open-circuit voltage
Nationell ämneskategori
Polymerteknologi Nanoteknik Annan fysik Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:umu:diva-166407 (URN)978-91-7855-170-5 (ISBN)978-91-7855-169-9 (ISBN)
Disputation
2020-01-09, Bio.A.206, Biologihuset, Umeå, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2019-12-19 Skapad: 2019-12-16 Senast uppdaterad: 2019-12-17Bibliografiskt granskad

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