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Umeå, Sweden

Asadpoordarvish A.,Umea University | Sandstrom A.,LunaLEC AB | Edman L.,Umea University
Advanced Engineering Materials | Year: 2016

The emerging field of organic electronics is heralded because it promises low-cost and flexible devices, and it was recently demonstrated that a light-emitting electrochemical cell (LEC) can be fabricated with cost-efficient methods under ambient air. However, the LEC turns sensitive to oxygen and water during light-emission, and it is therefore timely to identify flexible encapsulation structures. Here, we demonstrate that a multilayer film, featuring a water and oxygen barrier property of ≈1 × 10-3 g/m2/day and ≈1 × 10-3 cm3/m2/bar/day respectively, is fit for this task. By sandwiching an LEC between such multilayer barriers, as attached by a UV-curable epoxy, we realize flexible LECs with performance on par with identical glass-encapsulated devices, and which remain functional after one year storage under air. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sandstrom A.,Umea University | Sandstrom A.,LunaLEC AB | Asadpoordarvish A.,Umea University | Enevold J.,Umea University | Edman L.,Umea University
Advanced Materials | Year: 2014

Light-emitting electrochemical cells, featuring uniform and efficient light emission over areas of 200 cm2, 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. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A method for manufacturing a light-emitting electrochemical cell (LEC) is disclosed. The LEC comprises a first electrode, a second electrode, and a first light-emitting active material in electrical contact with and separating the first and second electrodes. The first active material comprises mobile ions in an amount sufficient for doping the active material. The method comprises a step of depositing the first active material by spray-coating at an ambient gas pressure of at least about 1 kPa.

Tang S.,Umea University | Tang S.,LunaLEC AB | Buchholz H.A.,Merck KGaA | Edman L.,Umea University | Edman L.,LunaLEC AB
Journal of Materials Chemistry C | Year: 2015

A light-emitting electrochemical cell (LEC) is characterized by its electrochemical doping operation that facilitates advantages as regards device fabrication and functionality, but it currently suffers from the drawback that the efficiency at significant luminance is not very high. A viable solution to this setback could be the implementation of a host-guest active material, where the majority host transports the electronic charge and the guest is a triplet emitter that features an appropriate energy structure for facile exciton transfer and trapping as well as for efficient light emission. Here, we demonstrate that an additional critical property of a functional host-guest LEC is that the host can be electrochemically p- and n-type doped, as can be deduced from screening studies on open planar devices and by cyclic voltammetry. LEC devices based on hosts that do not fulfill this fundamental criterion are shown to suffer from low luminance and poor efficiency, whereas host-guest LECs, based on a host material capable of electrochemical doping, exhibit a much improved luminance and efficiency, with the efficiency being well retained at high luminance values also. © The Royal Society of Chemistry.

Tang S.,Umea University | Tang S.,LunaLEC AB | Buchholz H.A.,Merck KGaA | Edman L.,Umea University | Edman L.,LunaLEC AB
ACS Applied Materials and Interfaces | Year: 2015

We report on the attainment of broadband white light emission from a host-guest light-emitting electrochemical cell, comprising a blue-emitting conjugated polymer as the majority host and a red-emitting small-molecule triplet emitter as the minority guest. An analysis of the energy structure reveals that host-to-guest energy transfer can be effectuated by both Förster and Dexter processes, and through a careful optimization of the active material composition partial energy transfer and white emission is accomplished at a low guest concentration of 0.5%. By adding a small amount of a yellow-emitting conjugated polymer to the active material, white light emission with a high color rendering index of 79, and an efficiency of 4.3 cd/A at significant luminance (>200 cd/m2), is realized. © 2015 American Chemical Society.

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