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.

A solution-based fabrication of fl exible and light-weight light-emitting devices on paper substrates is reported. Two different types of paper substrates are coated with a surface-emitting light-emitting electrochemical cell (LEC) device: a multilayer-coated specialty paper with an intermediate surface roughness of 0.4 µm and a low-end and low-cost copy paper with a large surface roughness of 5 µm. The entire device fabrication is executed using a handheld airbrush, and it is notable that all of the constituent layers are deposited from solution under ambient air. The top-emitting paper-LECs are highly fl exible, and display a uniform light emission with a luminance of 200 cd m −2 at a current conversion effi cacy of 1.4 cd A −1 .

The emerging field of printed electronics uses large amounts of printing and coating solvents during fabrication, which commonly are deposited and evaporated within spaces available to workers. It is in this context unfortunate that many of the currently employed solvents are non-desirable from health, safety, or environmental perspectives. Here, we address this issue through the development of a tool for the straightforward identification of functional and “green” replacement solvents. In short, the tool organizes a large set of solvents according to their Hansen solubility parameters, ink properties, and sustainability descriptors, and through systematic iteration delivers suggestions for green alternative solvents with similar dissolution capacity as the current non-sustainable solvent. We exemplify the merit of the tool in a case study on a multi-solute ink for high-performance light-emitting electrochemical cells, where a non-desired solvent was successfully replaced by two benign alternatives. The green-solvent selection tool is freely available at: www.opeg-umu.se/green-solvent-tool.

We report on the synthesis, characterization, and application of a series of metal-free near-infrared (NIR) emitting alternating donor/acceptor copolymers based on indacenodithieno[3,2-b]thiophene (IDTT) as the donor unit. A light-emitting electrochemical cell (LEC), comprising a blend of the copolymer poly[indacenodithieno[3,2-b]thiophene-2,8-diyl-alt-2,3-diphenyl-5,8-di(thiophen-2-yl)quinoxaline-5,5′-diyl] and an ionic liquid as the single-layer active material sandwiched between two air-stable electrodes, delivered NIR emission (λ peak = 705 nm) with a high radiance of 129 μW/cm 2 when driven by a low voltage of 3.4 V. The NIR-LEC also featured good stress stability, as manifested in that the peak NIR output from a nonencapsulated device after 24 h of continuous operation only had dropped by 3% under N 2 atmosphere and by 27% under ambient air. This work accordingly introduces IDTT-based donor/acceptor copolymers as functional metal-free electroluminescent materials in NIRemitting devices and also provides guidelines for how future NIR emitters should be designed for further improved performance.

The position of the emission zone (EZ) in the active material of a light‐emitting electrochemical cell (LEC) has a profound influence on its performance because of microcavity effects and doping‐ and electrode‐induced quenching. Previous attempts of EZ control have focused on the two principal constituents in the active material—the organic semiconductor (OSC) and the mobile ions—but this study demonstrates that it is possible to effectively control the EZ position through the inclusion of an appropriate additive into the active material. More specifically, it is shown that a mere modification of the end group on an added neutral compound, which also functions as an ion transporter, results in a shifted EZ from close to the anode to the center of the active material, which translates into a 60% improvement of the power efficiency. This particular finding is rationalized by a lowering of the effective electron mobility of the OSC through specific additive: OSC interactions, but the more important generic conclusion is that it is possible to control the EZ position, and thereby the LEC performance, by the straightforward inclusion of an easily tuned additive in the active material.

The organic light-emitting electrochemical cell (LEC) has emerged as an enabling technology for a wide range of novel and low-cost emissive applications, but its efficiency is still relatively modest. The focus in the field has so far almost exclusively been directed toward limiting internal loss mechanisms, whereas external losses resulting from poor light-outcoupling have been overlooked. Here, we report a straightforward procedure for improving the efficiency and emission quality of LECs. We find that our high-performance glass-encapsulated LECs exhibit a near-ideal Lambertian emission profile but that total internal reflection at the glass/air interface and a concomitant edge emission and self-absorption represent a significant loss factor. We demonstrate a 60% improvement in the outcoupled luminance in the forward direction by laminating a light-outcoupling film, featuring a hexagonal array of hemispherical microlenses as the surface structure, onto the front side of the device and a large-area metallic reflector onto the back side. With this scalable approach, yellow-emitting LEC devices with a power conversion efficiency of more than 15 lm W(-1) at a luminance of 100 cd m(-2) were realized. Importantly, we find that the same procedure also can mitigate problems with spatial variation in the light-emission intensity, which is a common and undesired feature of large-area LECs.

Alginates are derived from various species of brown seaweed found off the coasts of the North Atlantic, South America and Asia. They are produced as a range of salts, but sodium alginate is predominantly used in foods. Sodium alginate hydrates in cold or hot water to give viscous solutions. The controlled interaction between sodium alginate and calcium salts gives cold-setting gels that are shear irreversible and heat stable. Control is affected using citrate or phosphate sequestrants, or by processing at temperatures above about 70 • C and cooling. Typical food applications include reformed foods such as onion rings and olive fillings, cold-setting bakery cream fillings and heat-stable bakery and fruit fillings. Food Stabilisers, Thickeners and Gelling Agents Edited by Alan Imeson Macrosystis spp. Durvillaea spp.Fig. 4.1 Industrially utilised brown seaweeds. (Reproduced with kind permission of FMC Corporation.) For a colour version of this figure, please see Plate 2 of the colour plate section.been developed during more than 60 years of commercial utilisation. In food applications, alginate provides texturising properties such as thickening, stabilising and gelling. Brown algae require clean water with temperatures between 4 and 18 • C. As photosynthetic organisms, they are restricted to locations with appropriate light conditions, from the tidal zone to a depth of 50 m, depending on the species.The locations of brown algae industrially utilised for alginate production are shown in Fig. 4.1. The brown algae most widely used for the industrial production of alginate include Laminaria hyperborea, Laminaria digitata, Laminaria japonica, Ascophyllum nodosum, Ecklonia maxima, Macrocystis pyrifera, Durvillea antarctica, Lessonia nigrescens and Lessonia trabeculata. The plants are generally harvested from the sea or collected from the shore.Cultivation methods are also used, and an example of this is the cultivation of Laminaria japonica in China. It has been found difficult, and thereby too costly, to cultivate the other species mentioned, as these seaweeds cannot be grown simply from cuttings of mature plants. The regeneration would, in these cases, involve the production of spores from mature plants from which new plants could grow (McHugh, 2003).The alginate application, whether as thickener, stabiliser, gel former or film-forming agent, generally determines which seaweed is used as the source of alginate in order to achieve optimum performance. The global annual production of alginate is estimated at approximately 38 000 tonnes. ManufacturingAlginic acid is extracted from brown seaweed through a long and slow process. This is the free acid form of alginate and the water-insoluble intermediate in the commercial manufacture of alginates. Alginic acid has limited stability as chains are broken by auto-catalysed acid hydrolysis. In order to make stable, water-soluble alginate products, the alginic acid is 52 Food Stabilisers, Thickeners and Gelling Agents Fig. 4.2 Alginate salts produced from alginic acid for food use...

Flexible and high-aspect-ratio C(60) nanorods are synthesized using a liquid-liquid interfacial precipitation process. As-grown nanorods are shown to exhibit a hexagonal close-packed single-crystal structure, with m-dichlorobenzene solvent molecules incorporated into the crystalline structure in a C(60):m-dichlorobenzene ratio of 3:2. An annealing step at 200 °C transforms the nanorods into a solvent-free face-centred-cubic polycrystalline structure. The nanorods are deposited onto field-effect transistor structures using two solvent-based techniques: drop-casting and dip-coating. We find that dip-coating deposition results in a preferred alignment of non-bundled nanorods and a satisfying transistor performance. The latter is quantified by the attainment of an electron mobility of 0.08 cm (2) V(-1) s(-1) and an on/off ratio of > 10(4) for a single-crystal nanorod transistor, fabricated with a solution-based and low-temperature process that is compatible with flexible substrates.