Controlling the Emission Zone by Additives for Improved Light-Emitting Electrochemical Cells.

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.

A tool for identifying green solvents for printed electronics.

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 .

Thermally activated delayed fluorescence with 7% external quantum efficiency from a light-emitting electrochemical cell.

We report on light-emitting electrochemical cells, comprising a solution-processed single-layer active material and air-stabile electrodes, that exhibit efficient and bright thermally activated delayed fluorescence. Our optimized devices delivers a luminance of 120 cd m-2 at an external quantum efficiency of 7.0%. As such, it outperforms the combined luminance/efficiency state-of-the art for thermally activated delayed fluorescence light-emitting electrochemical cells by one order of magnitude. For this end, we employed a polymeric blend host for balanced electrochemical doping and electronic transport as well as uniform film formation, an optimized concentration (<1 mass%) of guest for complete host-to-guest energy transfer at minimized aggregation and efficient emission, and an appropriate concentration of an electrochemically stabile electrolyte for desired doping effects. The generic nature of our approach is manifested in the attainment of bright and efficient thermally activated delayed fluorescence emission from three different light-emitting electrochemical cells with invariant host:guest:electrolyte number ratio.

Oligomer Electrolytes for Light-Emitting Electrochemical Cells: Influence of the End Groups on Ion Coordination, Ion Binding, and Turn-on Kinetics.

The electrolyte is an essential constituent of the light-emitting electrochemical cell (LEC), since its operating mechanism is dependent on the redistribution of mobile ions in the active layer. Recent developments of new ion transporters have yielded high-performance devices, but knowledge about the interactions between the ionic species and the ion transporters and the influence of these interactions on the LEC performance is lacking. We therefore present a combined computational and experimental effort that demonstrates that the selection of the end group in a star-branched oligomeric ion transporter based on trimethylolpropane ethoxylate has a paramount influence on the ionic interactions in the electrolyte and thereby also on the performance of the corresponding LECs. With hydroxyl end groups, the cation from the salt is strongly coordinated to the ion transporter, which leads to suppression of ion pairing, but the penalty is a hindered ion release and a slow turn-on for the LEC devices. With methoxy end groups, an intermediate coordination strength is seen together with the formation of contact ion pairs, but the LEC performance is very good with fast turn-on. Using a series of ion transporters with alkyl carbonate end groups, the ion transporter:cation coordination strength is lowered further, but the turn-on kinetics are slower than what is seen for devices comprising the methoxy end-capped ion transporter.

Optical analysis of light-emitting electrochemical cells.

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.

Challenging Conventional Wisdom: Finding High-Performance Electrodes for Light-Emitting Electrochemical Cells.

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.

Publisher Correction: The Weak Microcavity as an Enabler for Bright and Fault-tolerant Light-emitting Electrochemical Cells.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

The Weak Microcavity as an Enabler for Bright and Fault-tolerant Light-emitting Electrochemical Cells.

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.

Toward Efficient and Metal-Free Emissive Devices: A Solution-Processed Host-Guest Light-Emitting Electrochemical Cell Featuring Thermally Activated Delayed Fluorescence.

The next generation of emissive devices should preferably be efficient, low-cost, and environmentally sustainable, and as such utilize all electrically generated excitons (both singlets and triplets) for the light emission, while being free from rare metals such as iridium. Here, we report on a step toward this vision through the design, fabrication, and operation of a host-guest light-emitting electrochemical cell (LEC) featuring an organic thermally activated delayed fluorescence (TADF) guest that harvests both singlet and triplet excitons for the emission. The rare-metal-free active material also consists of a polymeric electrolyte and a polymeric compatibilizer for the facilitation of a cost-efficient and scalable solution-based fabrication, and for the use of air-stable electrodes. We report that such TADF-LEC devices can deliver uniform green light emission with a maximum luminance of 228 cd m-2 when driven by a constant-current density of 770 A m-2, and 760 cd m-2 during a voltage ramp, which represents a one-order-of-magnitude improvement in comparison to previous TADF-emitting LECs.

Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by 2H MAS NMR.

The organization of water molecules adsorbed onto cellulose and the supramolecular hydrated structure of microfibril aggregates represents, still today, one of the open and complex questions in the physical chemistry of natural polymers. Here, we investigate by 2H MAS NMR the mobility of water molecules in carefully 2H-exchanged, and thereafter re-dried, microcrystalline cellulose. By subtracting the spectral contribution of deuteroxyls from the spectrum of hydrated cellulose, we demonstrate the existence of two distinct 2H2O spectral populations associated with mobile and immobile water environments, between which the water molecules do not exchange at the NMR observation time scale. We conclude that those two water phases are located at differently-accessible adsorption sites, here assigned to the cellulose surfaces between and within the microfibril aggregates, respectively. The superior performance of 2H MAS NMR encourages further applications of the same method to other complex systems that expose heterogeneous hygroscopic surfaces, like wood cell walls.

Site-resolved (2)H relaxation experiments in solid materials by global line-shape analysis of MAS NMR spectra.

We investigate a way one can achieve good spectral resolution in (2)H MAS NMR experiments. The goal is to be able to distinguish between and study sites in various deuterated materials with small chemical shift dispersion. We show that the (2)H MAS NMR spectra recorded during a spin-relaxation experiment are amenable to spectral decomposition because of the different evolution of spectral components during the relaxation delay. We verify that the results are robust by global least-square fitting of the spectral series both under the assumption of specific line shapes and without such assumptions (COmponent-REsolved spectroscopy, CORE). In addition, we investigate the reliability of the developed protocol by analyzing spectra simulated with different combinations of spectral parameters. The performance is demonstrated in a model material of deuterated poly(methacrylic acid) that contains two (2)H spin populations with similar chemical shifts but different quadrupole splittings. In (2)H-exchanged cellulose containing two (2)H spin populations with very similar chemical shifts and quadrupole splittings, the method provides new site-selective information about the molecular dynamics.

Inkjet printed bilayer light-emitting electrochemical cells for display and lighting applications.

A new bilayer light-emitting electrochemical cell (LEC) device, which allows well-defined patterned light emission through an easily adjustable, mask-free, and additive fabrication process, is reported. The bilayer stack comprises an inkjet-printed lattice of micrometer-sized electrolyte droplets, in a "filled" or "patterned" lattice configuration. On top of this, a thin layer of light-emitting compound is deposited from solution. The light emission is demonstrated to originate from regions proximate to the interfaces between the inkjetted electrolyte, the light-emitting compound, and one electrode, where bipolar electron/hole injection and electrochemical doping are facilitated by ion motion. By employing KCF3 SO3 in poly(ethylene glycol) as the electrolyte, Super Yellow as the light-emitting compound, and two air-stabile electrodes, it is possible to realize filled lattice devices that feature uniform yellow-green light emission to the naked eye, and patterned lattice devices that deliver well-defined and high-contrast static messages with a pixel density of 170 PPI.

Study description and baseline characteristics of the population enrolled in a multinational observational study of extended teriparatide use (ExFOS).

OBJECTIVE: To better characterize patients who are currently being prescribed teriparatide in Europe, this article describes the study design and baseline characteristics of participants of the Extended Forsteo * Observational Study (ExFOS). RESEARCH DESIGN AND METHODS: ExFOS is a noninterventional, multicenter, prospective, observational study in men and women with osteoporosis treated with teriparatide during the course of normal clinical practice for up to 24 months and with a post-treatment follow-up of at least 18 months. MAIN OUTCOME MEASURES: Baseline characteristics, including history of fracture and back pain, and health-related quality of life (HRQoL, assessed using the EuroQol-5 Dimension [EQ-5D]). RESULTS: Of 1607 patients enrolled, 90.9% were women. At baseline, mean (standard deviation [SD]) age was 70.3 (9.8) years, and 85.8% of patients had a history of fracture (64.7% with ≥2 fragility fractures). Of those with historic fractures, 90.8% had vertebral fractures (67.8% had thoracic fractures). The mean (SD) of reported bone mineral density T-scores were -3.0 (1.2), -2.4 (1.0), and -2.5 (0.9) for lumbar spine, total hip (left), and femoral neck (left), respectively. Overall, 39.3% of patients had experienced ≥1 fall during the 12 months before enrollment. At baseline, 11.4% of patients were osteoporosis-treatment naïve and 15% were currently using glucocorticoids. The mean (SD) visual analog scale score for back pain during the last month was 50.7 (26.9), and 62.1% of patients experienced daily or almost daily back pain. The median EQ-5D health state value at baseline was 0.62 (first and third quartiles: 0.19, 0.74). CONCLUSIONS: Baseline characteristics of the ExFOS study cohort indicate that patients prescribed teriparatide in Europe have severe osteoporosis with highly prevalent vertebral fractures, frequent and disabling back pain, and a poor HRQoL, despite previous pharmacotherapy for osteoporosis. Limitations include non-randomization, lack of a comparator group, and patient self-report for data on prior medication and fracture history.

Increased fracture rate in diabetes mellitus and females after renal transplantation.

BACKGROUND: Bone disease and fractures after organ transplantation pose severe clinical problems. About 20% of renal transplant patients have type 1 diabetes (IDDM). However, data are scarce in the literature about the occurrence of spontaneous fractures in IDDM patients posttransplantation. METHODS: In this cross-sectional study using a questionnaire and hospital records the prevalence of symptomatic bone disease was investigated in 193 renal transplanted patients with functioning renal grafts 6 months to 23 years after the transplantation. RESULTS: The frequency of IDDM was 18%. In the total group the rate of osteoporotic fractures posttransplantation was 17%, and the majority of fractures occurred within the first 3 years after the transplantation. A high rate of fractures, 40%, was noted in the diabetes group (P<0.001), compared with 11% in the nondiabetes group. Fractures seen in IDDM were often multiple and located mostly in the appendicular skeleton, i.e., in ankles and feet. Female gender was also associated with an elevated fracture rate, 23% (P<0.05). CONCLUSION: An increased incidence of osteoporotic fractures after renal transplantation was found in diabetic and female patients. The mechanism behind bone fragility in IDDM is multifactorial and despite a restored renal function bone disease may progress, and is probably enhanced by the immunosuppressive treatment.

Reduced serum levels of the growth hormone-dependent insulin-like growth factor binding protein and a negative bone balance at the level of individual remodeling units in idiopathic osteoporosis in men.

Idiopathic osteoporosis in younger individuals could be related to reduced bone formation rather than increased bone resorption, and disturbances in GH or insulin-like growth factor (IGF)-I production could be involved in its pathogenesis. In the present study, men with idiopathic osteoporosis were compared with healthy men, with respect to bone histomorphometry and to serum levels of IGF-I, IGF-II, IGF binding protein (IGFBP)-2 and IGFBP-3, and 24-h urinary excretion of GH. Mean wall thickness was reduced in the patients (48.3 +/- 7.2 vs. 61.7 +/- 5.4 microns, P < 0.001). Also, resorption depth was decreased, albeit to a lesser degree (54.4 +/- 3.8 vs. 60.7 +/- 5.3 microns, P < 0.01), thus creating a pronounced negative balance (-6.04 +/- 9.8 vs. 0.96 +/- 3.2 microns, P < 0.05). In the patients, serum concentrations of IGFBP-3 were reduced, compared with controls, with a 46% lower mean value; whereas levels of IGF-I, IGF-II, IGFBP-2, and GH were similar in the two groups. Thus, there was a significant negative balance caused by a pronounced decrease in wall thickness in men with idiopathic osteoporosis. The finding of low IGFBP-3 levels in these patients is interesting, in view of previous clinical and experimental findings, but its pathophysiological significance remains to be determined.

Regulation of interleukin-6 secretion from mononuclear blood cells by extracellular calcium.

Interleukin-6 (IL-6) is known to enhance osteoclast recruitment, and thereby bone resorption. Thus, IL-6 has been proposed to mediate hypercalcemia in multiple myeloma and the enhanced osteoclastic activity seen in postmenopausal osteoporosis. We recently reported that the calcium concentration in plasma affects IL-6 secretion from mononuclear blood cells. To investigate the underlying mechanism, we have studied the effect of calcium on IL-6 formation in mononuclear blood cells ex vivo and in vitro. Thirteen healthy volunteers were given 1 g of calcium orally after overnight fasting. Plasma levels of ionized calcium (pCa2+) and serum levels of parathyroid hormone (sPTH) were measured after 2 and 4 h, with all subjects still fasting. After 2 h, pCa2+ was increased and sPTH decreased in all 13 persons. IL-6 secretion ex vivo from mononuclear blood cells drawn 4 h after calcium intake was increased 185% as compared with IL-6 secretion from cells drawn just before calcium intake. In control experiments without calcium intake, there was no alteration in pCa2+ and no effect on IL-6 secretion from mononuclear blood cells. In vitro studies revealed that stimulation of isolated mononuclear blood cells with physiological concentrations of calcium dose-dependently increased IL-6 secretion with an estimated EC50 at 1.2 mM Ca2+. No effect on the IL-6 secretion was seen following treatment of the isolated mononuclear blood cells with PTH or calcitonin. These observations demonstrate that the plasma calcium concentration affects IL-6 secretion from mononuclear blood cells. The in vitro data indicate the involvement of a direct calcium sensing mechanism. These findings might have implications in hypercalcemia and should also be borne in mind when considering the role of cytokines in osteoporosis.

Effects of growth hormone and insulin-like growth factor I in men with idiopathic osteoporosis.

Injections with growth hormone (GH) or insulin-like growth factor I (IGF-I) have been proposed for anabolic therapy in osteoporosis. In a cross-over study, 12 men with idiopathic osteoporosis received daily subcutaneous injections of GH (2 IU/m2) or IGF-I (80 micrograms/kg) for 7 days with 12 weeks of wash-out. Serum levels of procollagen type I increased by 29% following treatment with GH (P < 0.001) and by 43% with IGF-I (P < 0.001 compared with pretreatment levels; P < 0.05 compared with GH injections), whereas both treatments rendered a 20% increase in osteocalcin concentrations (P < 0.001), indicating enhanced bone formation. There was also evidence of stimulated bone resorption, as the urinary levels of deoxypyridinoline increased by 44% following GH injections (P < 0.001) and by 29% following IGF-I (P < 0.001), and there were 28% higher serum concentrations of IGF-I after GH than after IGF-I injections. Although markers of bone metabolism increased under both treatments, comparison of the treatments suggests that IGF-I enhanced formation of collagen type I more than did GH. Furthermore, the stimulation of bone resorption was detected as soon as 4 days after the initiation of GH injections. Some of the differences might be dose-dependent, but could also indicate separate mechanisms at the cellular level.

Carbon dioxide laser miniconization for treatment of human papillomavirus infection associated with cervical intraepithelial neoplasia.

BACKGROUND: The effect of the carbon dioxide laser miniconization for treatment of cervical intraepithelial neoplasia with concomitant human papillomavirus infection was evaluated. MATERIAL AND METHODS: One hundred and eighteen women with cytologically proven cervical intraepithelial neoplasia stage 1 and/or 2 were investigated with repeat vaginal smear, colposcopy and human papillomavirus DNA sampling. Seventy-five out of 118 women were subjected to laser miniconization or punch biopsy and cervical curettage. RESULTS: Out of 118 patients 37 proved to have positive human papillomavirus DNA with one or more oncogenic types (31.4%). Of these, 32 women were miniconized and five subjected to punch biopsy or cervical curettage. On the first follow-up after miniconization all 32 patients were HPV negative. With follow-up up to five years no recurrences of HPV or dysplasia were seen. CONCLUSION: A miniconization procedure with carbon dioxide laser for treatment of cervical intraepithelial neoplasia proved useful also for simultaneous therapy of concomitant human papillomavirus infection of the uterine cervix.

Lead intoxication caused by skeletal disease.

BACKGROUND: Inorganic lead is accumulated in the skeleton, which harbors more than 90% of the body burden of lead. If rapidly mobilized, this pool may constitute a health risk. However, clear evidence of this theory has been lacking. HISTORY: A previously healthy 36-year-old Swedish man with more than 10 years of work-related lead exposure developed headache, musculoskeletal pain, and paresthesia of both arms. Two months after the cessation of exposure, the lead level in his blood (B-Pb) was 5.5 mumol.l-1, and treatment with chelating agents was started. Shortly after the treatment period, he had an accident causing a fracture of the right collum femoris. The B-Pb was fairly stable around 1.5 mumol.l-1 for about two years after the end of exposure (95th percentile 0.6 mumol.l-1 for occupationally unexposed Swedish men). The examination showed that the patient had high skeletal turnover and clearly reduced bone density, as well as signs of tubular dysfunction. He was given the diagnosis idiopathic osteoporosis. His moderately raised bone lead concentration (about 20 micrograms.g wet weight-1; normal level in Sweden 4 micrograms.g-1) can only partly explain the raised B-Pb, remaining for years after the cessation of exposure. Instead, the main explanation is probably the increased skeletal turnover. CONCLUSIONS: A combination of a moderately increased bone lead pool and skeletal disease seems to increase the risk for lead poisoning.

Hormonal regulation of serum lipoprotein(a) levels. Contrasting effects of growth hormone and insulin-like growth factor-I.

In response to treatment with growth hormone, serum levels of lipoprotein(a) increase, while those of LDL cholesterol decrease. To establish if increased levels of insulin-like growth factor-I may be of importance for these changes, we analyzed serum lipoprotein concentrations in 11 male patients with idiopathic osteoporosis who were treated with growth hormone (2 IU.m-2.d-1) or insulin-like growth factor-I (80 micrograms.kg-1.d-1) in a randomized, double-blind, cross-over study. LDL cholesterol was reduced by 0.7 mmol/L (P < .01) during growth hormone treatment but was not affected when the same patients received insulin-like growth factor-I. In contrast, mean lipoprotein(a) levels increased from 519 to 571 mg/L (P < .03) in response to growth hormone but were reduced from 538 to 478 mg/L (P < .04) during treatment with insulin-like growth factor-I. These results indicate that growth hormone exerts its effects on lipoprotein metabolism independent of insulin-like growth factor-I. Furthermore, the results suggest that treatment with insulin-like growth factor-I may reduce lipoprotein(a) levels.