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Hydnum is a genus of ectomycorrhizal fungi belonging to the Hydnaceae family. It is widely distributed across different regions of the world, including North America, Europe, and Asia; however, some of them showed disjunct distributions. In recent years, with the integration of molecular techniques, the taxonomy and classification of Hydnum have undergone several revisions and advancements. However, these changes have not yet been applied in the Republic of Korea. In this study, we conducted an integrated analysis combining the morphological and molecular analyses of 30 specimens collected over a period of approximately 10 years in the Republic of Korea. For molecular analysis, the sequence data of the internal transcribed spacer (ITS) region, the large subunit of nuclear ribosomal RNA gene (nrLSU), and a portion of translation elongation factor 1-α (TEF1) were employed as molecular markers. Through this study, we identified eight species that had previously not been reported to occur in the Republic of Korea, including one new species, Hydnum paucispinum. A taxonomic key and detailed descriptions of the eight Hydnum species are provided in this study. [ABSTRACT FROM AUTHOR]

Cladosporium species are cosmopolitan fungi, characterized by olivaceous or dark colonies with coronate conidiogenous loci and conidial hila with a central convex dome surrounded by a raised periclinal rim. Cladosporium species have also been discovered in marine environments. Although many studies have been performed on the application of marine originated Cladosporium species, taxonomic studies on these species are scarce. We isolated Cladosporium species from three under-studied habitats (sediment, seawater, and seaweed) in two districts including an intertidal zone in the Republic of Korea and the open sea in the Western Pacific Ocean. Based on multigenetic marker analyses (for the internal transcribed spacer, actin, and translation elongation factor 1), we identified fourteen species, of which five were found to represent new species. These five species were C. lagenariiforme sp. nov., C. maltirimosum sp. nov., C. marinum sp. nov. in the C. cladosporioides species complex, C. snafimbriatum sp. nov. in the C. herbarum species complex, and C. marinisedimentum sp. nov. in the C. sphaerospermum species complex. Morphological characteristics of the new species and aspects of differences with the already known species are described herein together with molecular data. [ABSTRACT FROM AUTHOR]

Plastic wastes have a negative impact on marine environments; however, they can be used as carbon sources and habitats by certain microbes. Microbes in the marine plastisphere can migrate worldwide through the ocean and cause serious environmental problems when they encounter suitable environments. Therefore, efforts to investigate the microbes inhabiting the marine plastisphere are increasing. In the present study, fungal strains were isolated from plastic wastes buried in Korean sea sands and mudflats and identified using molecular and morphological analyses. Five species were identified that were previously unrecorded from South Korea: Cladosporium funiculosum, Neosetophoma poaceicola, Neosetophoma rosigena, Parasarocladium gamsii, and Trichoderma fomiticola. Their molecular phylogenies and morphological characteristics are described in this study. [ABSTRACT FROM AUTHOR]

Collybiopsis is a genus of the gymnopoid/marasmioid complex of the family Omphalotaceae. The classification system of Collybiopsis has recently undergone large changes through molecular approaches. The new classification system has not been applied for Collybiopsis in the Republic of Korea, and general research on this genus was also lacking. In this study, we analyzed the Collybiopsis species in the Republic of Korea by assessing all gymnopoid/marasmioid specimens collected nationwide for ten years by combining morphological approaches and multilocus (ITS + nrLSU) phylogenetic analysis. We thus confirmed that 16 species of Collybiopsis are present in the Republic of Korea, including two previously unreported species (Co. nonnulla and Co. dichroa) and seven new species (Co. albicantipes sp. nov., Co. clavicystidiata sp. nov., Co. fulva sp. nov., Co. orientisubnuda sp. nov., Co. subumbilicata sp. nov., Co. undulata sp. nov., and Co. vellerea sp. nov.). A thorough examination of the Collybiopsis suggested that it is difficult to distinguish or identify the species based on morphological characteristics only; a combined molecular approach is needed for accurate identification. The Collybiopsis database of the Republic of Korea is updated, and information on the new species is provided. Five new combinations from Marasmiellus to Collybiopsis are also proposed (Co. istanbulensis comb. nov., Co. koreana comb. nov., Co. omphalodes comb. nov., Co. pseudomphalodes comb. nov., and Co. ramuliciola comb. nov.). [ABSTRACT FROM AUTHOR]

Genus Xylodon consists of white-rot fungi that grow on both angiosperms and gymnosperms. With resupinate and adnate basidiomes, Xylodon species have been classified into other resupinate genera for a long time. Upon the integration of molecular assessments, the taxonomy of the genus has been revised multiple times over the years. However, the emendations were poorly reflected in studies and public sequence databases. In the present study, the genus Xylodon in Korea was evaluated using molecular and morphological analyses of 172 specimens collected in the period of 2011 to 2018. The host types and geographical distributions were also determined for species delimitation. Furthermore, public sequences that correspond to the Xylodon species in Korea were assessed to validate their identities. Nine Xylodon species were identified in Korea, with three species new to the country. Morphological differentiation and identification of some species were challenging, but all nine species were clearly divided into well-resolved clades in the phylogenetic analyses. Detailed species descriptions, phylogeny, and a key to Xylodon species in Korea are provided in the present study. A total of 646 public ITS and nrLSU sequences corresponding to the nine Xylodon species were found, each with 404 (73.1%) and 57 (61.3%) misidentified or labeled with synonymous names. In many cases, sequences released before the report of new names have not been revised or updated. Revisions of these sequences are arranged in the present study. These amendments may be used to avoid the misidentification of future sequence-based identifications and concurrently prevent the accumulation of misidentified sequences in GenBank. [ABSTRACT FROM AUTHOR]

The genus Laccaria (Hydnangiaceae, Agaricales) plays an important role in forest ecosystems as an ectomycorrhizal fungus, contributing to nutrient cycles through symbiosis with many types of trees. Though understanding Laccaria diversity and distribution patterns, as well as its association with host plants, is fundamental to constructing a balanced plant diversity and conducting effective forest management, previous studies have not been effective in accurately investigating, as they relied heavily on specimen collection alone. To investigate the true diversity and distribution pattern of Laccaria species and determine their host types, we used four different approaches: specimen-based analysis, open database search (ODS), NGS analysis, and species-specific PCR (SSP). As a result, 14 Laccaria species have been confirmed in Korea. Results regarding the species distribution pattern were different between specimen-based analysis and SSP. However, when both were integrated, the exact distribution pattern of each Laccaria species was determined. In addition, the SSP revealed that many Laccaria species have a wide range of host types. This study shows that using these four different approaches is useful in determining the diversity, distribution, and host of ECM fungi. Furthermore, results obtained for Laccaria will serve as a baseline to help understand the role of ECM fungi in forest management in response to climate change. [ABSTRACT FROM AUTHOR]

We report on the electrochemical stability of hole polarons in three conjugated polymers probed by resonant Raman spectroscopy. The materials considered are all isostructural to poly(3- hexyl)thiophene, where thiazole units have been included to systematically deepen the energy level of the highest occupied molecular orbital (HOMO). We demonstrate that increasing the thiazole content planarizes the main conjugated backbone of the polymer and improves the electrochemical stability in the ground state. However, these more planar thiazole containing polymers are increasingly susceptible to electrochemical degradation in the polaronic excited state. We identify the degradation mechanism, which targets the C==N bond in the thiazole units and results in disruption of the main polymer backbone conjugation. The introduction of thiazole units to deepen the HOMO energy level and increase the conjugated backbone planarity can be beneficial for the performance of certain optoelectronic devices, but the reduced electrochemical stability of the hole polaron may compromise their operational stability. [ABSTRACT FROM AUTHOR]

Quantum-chemical calculations performed on poly[2,7-(9,9-di-n-octylfluorene)(1-x)-co-4,7-(2,1,3-benzothiadiazole)(x)] copolymers (0≤x≤0.5) show that the lowest unoccupied molecular orbital is always highly localized on the benzothiadiazole (BT) units while the highest occupied molecular orbital is delocalized over the whole chain. Chains with a low BT content are characterized by a reduced oscillator strength of the lowest optical transition and by an increased charge-transfer character of the exciton. These results are supported experimentally by a blueshift of the lowest energy absorption band upon reduction in the BT ratio, lower photoluminescence efficiency, longer excited state lifetimes, and greater solvent dependence of the emission properties. [ABSTRACT FROM AUTHOR]

We examine the photophysical properties of ladder-type pentaphenylenes, which have been prepared as prototypical “all-in-one” emissive materials bearing both electron-accepting (diaryloxadiazole) and electron-donating (triphenylamine) units. We find that donor-acceptor interactions are very dependent on the nature of the connectivity of these groups to the main pentaphenylene chain. When the oxadiazole and triphenylamine units were substituted on opposite sides of the π-conjugated pentaphenylene chromophore, photoluminescence with long lifetimes typical of exciplex-like species was observed, while being significantly quenched by intermolecular charge separation between the substituents. By contrast, when the triphenylamine units were attached at the ends of the chromophore, no such effects were observed and a blue/green photoluminescence was obtained with very high quantum efficiency. In this latter configuration, evidence of ambipolar charge transport and a blue/green electroluminescence were additionally observed. [ABSTRACT FROM AUTHOR]

Grazing angle photoluminescence (GPL) originates from a waveguided light emitted at grazing angle to the substrate due to the total internal reflections, and the light emission is polarized with enhanced intensity at selective mode wavelength. GPL measurements reveal the optical anisotropy of luminescent conjugated polymers, in particular, the alignment of emitting dipoles from which emission occurs, in contrast to spectroscopic ellipsometry measurements that give the anisotropy in the absorption. Based on the GPL emission intensities and spectra, we investigate the anisotropic optical properties in electroluminescent poly(9,9′-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) conjugated polymer thin films of different molecular weights (Mn=9–255 kg/mol), both in the pristine and annealed states. The optical anisotropy in F8BT films generally increases with molecular weight, suggesting that higher molecular weight polymers with longer chains are more likely to lie in-plane to the substrate. Upon annealing, high molecular weight F8BT films show even a higher degree of anisotropy, in contrast to low molecular weight F8BT films that become more isotropic. Annealing causes the polymer chains to rearrange and adopt a configuration in which the interchain exciton migration to better ordered low energy (LE) emissive states is strongly suppressed. We observe that the emissive states in F8BT are strongly affected by the local polymer chain arrangement, producing the less ordered high energy (HE) emissive states near the substrate interface where there is a higher degree of chain disorder and the LE states in the bulk of the film. When spin coated onto a quartz substrate precoated with a poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) layer, films of F8BT show severe luminescence quenching near the PEDOT:PSS interface for both the LE and HE emissive states, but a selective quenching of the LE states in the bulk of the film. These observations have important implications for fabricating efficient electronic devices using conjugated polymers as an active material, since the performance of these devices will strongly depend on anisotropic optical properties of electroluminescent conjugated polymers. [ABSTRACT FROM AUTHOR]

Characterizes the electroluminescence pattern emitted through the surface and edge of the glass substrate of two efficient polymer light-emitting diodes (LED). Lambertian nature of surface emission; Discrete substrate reflection and leaky waveguide modes of edge emission; Optical model accounting for optical interference effects of the metal cathode-reflector.

Ankle brachial index (ABI) and brachial-ankle pulse wave velocity (baPWV) are widely used noninvasive modalities to evaluate atherosclerosis. Recently, evidence has increased supporting the use of ABI and baPWV as markers of cerebrovascular disease. This study sought to examine the relationship between ABI and baPWV with ischemic stroke. This study also aimed to determine which pathogenic mechanism, large artery disease (LAD) or small vessel disease (SVD), is related to ABI or baPWV. Retrospectively, 121 patients with ischemic stroke and 38 subjects with no obvious ischemic stroke history were recruited. First, ABI and baPWV were compared between the groups. Then, within the stroke group, the relevance of ABI and baPWV with regard to SVD and LAD, which were classified by brain magnetic resonance image (MRI) and magnetic resonance angiography (MRA) or computed tomography angiography (CTA) findings, was assessed. The baPWV was higher in the stroke group than non-stroke group (1,944.18±416.6 cm/s vs. 1,749.76±669.6 cm/s, P<0.01). Regarding LAD, we found that mean ABI value was lower in the group with extracranial large artery stenosis (P<0.01), and there was an inverse linear correlation between ABI and the grade of extracranial large artery stenosis (P<0.01). For SVD, there was a significant correlation between SVD and baPWV (2,057.6±456.57 cm/s in the SVD (+) group vs. 1,491±271.62 cm/s in the SVD (-) group; P<0.01). However, the grade of abnormalities detected in SVD did not correlate linearly with baPWV. These findings show that baPWVis a reliable surrogate marker of ischemic stroke. Furthermore, baPWVand ABI can be used to indicate the presence of small vessel disease and large arterial disease, respectively. [ABSTRACT FROM AUTHOR]

The performance of hybrid (organic-inorganic) photovoltaic devices is critically dependent on the thin film morphology. This work studies the film formation process using the in situ thermal decomposition of a soluble precursor to form a well-distributed network of CdS nanoparticles within a poly(3-hexylthiophene) (P3HT) polymer matrix. Resonant Raman spectroscopy is used to probe the formation of the inorganic nanoparticles and the corresponding changes in the molecular order of the polymer. We find that the CdS precursor decomposes rapidly upon heating to 160 °C, but that this has a disruptive effect on the P3HT. The extent of this disruption can be controlled by adjusting the annealing temperature, and nanowire aggregates of P3HT are found to have increased susceptibility. Atomic force microscopy reveals that at high temperatures (>200 °C), cracks form in the film, resulting in a 'plateau'-like microstructure. In order to retain the preferable 'granular' microstructure and to control the molecular disruption, low decomposition temperatures are needed. This work identifies a particular problem for optimising the hybrid thin film morphology and shows how it can be partially overcome. [ABSTRACT FROM AUTHOR]

Background: Behcet's disease is a heterogeneous, multisystem, inflammatory disorder of unknown etiology. The classic triad of oral and genital ulcerations in conjunction with uveitis was originally described by the Turkish dermatologist Hulusi Behcet in 1937, but associated symptoms of the cardiovascular, central nervous, pulmonary, and gastrointestinal systems were later identified. In fact, Behcet's disease with neurological involvement (neuro-Behcet's disease) is not uncommon. Patients with neuro-Behcet's disease typically exhibit a diverse array of symptoms, most commonly in the brainstem and diencephalic regions. Herein, we report an unusual case of neuro-Behcet's disease in a patient who presented with a solitary cerebellar hemorrhage.Case Presentation: A 39-year-old Asian woman was admitted to our hospital with complaints of a sudden speech difficulty that had manifested the same morning, and dizziness and mild vomiting experienced over the previous 3 days. Magnetic resonance images revealed target-like hemorrhagic lesions in the right hemisphere of the cerebellum. Risk factors that may result in cerebellar hemorrhage, such as high blood pressure or bleeding diathesis, were ruled out, and subsequent brain angiograms were normal.Conclusions: These findings suggest that the patient's cerebellar hemorrhage could have been due to intracranial vasculitis in a rare, if not unique, complication of neuro-Behcet's disease. [ABSTRACT FROM AUTHOR]

We describe a spectroelectrochemical approach to accelerated electrochemical stability studies of conjugated polymers under oxidative stress. The polaron stabilities of alternating copolymers based on (i) thiophene and thiazole, namely PTTz, and (ii) bithiophene and thiazole, namely PTTTz, are compared in neat films with that of P3HT. P3HT is found to be the most stable whilst PTTz is found to be the least stable. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is characterized by progressive dopaminergic cell loss in the substantia nigra (SN) and elevated iron levels demonstrated by autopsy. Direct visualization of iron with live imaging techniques has not yet been successful. The aim of this study is to visualize and quantify the distribution of cellular iron using an intrinsic iron hyperspectral fluorescence signal. The 1-methyl-4-phenylpyridinium (MPP+)-induced cellular model of PD was established in SHSY5Y cells exposed to iron with ferric ammonium citrate (FAC, 100 μM). The hyperspectral fluorescence signal of iron was examined using a high-resolution dark-field optical microscope system with signal absorption for the visible/near infrared spectral range. The 6-h group showed heavy cellular iron deposition compared with the 1 -h group. The cellular iron was dispersed in a small particulate form, whereas the extracellular iron was aggregated. In addition, iron particles were found to be concentrated on the cell membrane/edge of shrunken cells. The iron accumulation readily occurred in MPP+-induced cells, which is consistent with previous studies demonstrating elevated iron levels in the SN. This direct iron imaging could be applied to analyze the physiological role of iron, and its application might be expanded to various neurological disorders involving metals, such as copper, manganese, or zinc. [ABSTRACT FROM AUTHOR]

In this study, the effect of Codonopsis lanceolata fermented by lactic acid on controlling gene expression levels related to obesity was observed in an oligonucleotide chip microarray. Among 8170 genes, 393 genes were up regulated and 760 genes were down regulated in feeding the fermented C. lanceolata (FCL). Another 374 genes were up regulated and 527 genes down regulated without feeding the sample. The genes were not affected by the FCL sample. It was interesting that among those genes, Chytochrome P450, Dmbt1, LOC76487, and thyroid hormones, etc., were mostly up or down regulated. These genes are more related to lipid synthesis. We could conclude that the FCL possibly controlled the gene expression levels related to lipid synthesis, which resulted in reducing obesity. However, more detailed protein expression experiments should be carried out. [ABSTRACT FROM AUTHOR]

Background: Ropinirole prolonged release (RPR) is a once-daily formulation. However, there may be individual pharmacokinetic differences so that multiple dosing may be preferred in some individuals. This study compares once-daily and twice-daily RPR in patients with Parkinson's disease. Methods: This study was an open-label crossover study. We enrolled Parkinson's disease patients on dopamine agonist therapy with unsatisfactory control such as motor fluctuation, dyskinesia and sleep-related problems. Agonists were switched into equivalent dose of RPR. Subjects were consecutively enrolled into either once-daily first or twice-daily first groups, and received the same amount of RPR in a single and two divided dosing for 8 weeks respectively in a crossover manner without a washout period. The primary outcome was a questionnaire of the preference completed by patients in the last visit. The secondary outcome measures included the Unified Parkinson's Disease Rating Scale part 3 (mUPDRS), Hoehn and Yahr stage (H&Y); sleep questionnaire including overall quality of sleep, nocturnal off symptoms and early morning symptoms; Epworth Sleep Scale (ESS); compliances and patient global impression (PGI). Results: A total of 82 patients were enrolled and 61 completed the study. 31 patients preferred twice-daily regimen, 17 preferred the once-daily regimen, and 13 had no preference. Their mean mUPDRS, H&Y, ESS, sleep quality, compliance and adverse events were not statistically different in both regimens. PGI-improvement on wearing off defined was better in twice-daily dosing regimen. Conclusions: RPR is a once-daily formulation, but multiple dosing was preferred in many patients. Multiple dosing of RPR might be a therapeutic option if once-daily dosing is unsatisfactory. [ABSTRACT FROM AUTHOR]

Codonopsis lanceolata (Campanulaceae) have been traditionally used to treat lung inflammatory diseases, such as asthma, tonsillitis, and pharyngitis. The present study was performed to evaluate the cognitive-enhancing effects of steamed and fermented C. lanceolata in scopolamine-induced memory impairments in mice. Cognitive abilities were determined by the Morris water maze and passive avoidance tests. Mice orally Received fermented C. lanceolata extract at doses of 100, 300, or 500 mg/kg body weight. Fermented C. lanceolata extract (500 mg/kg body weight, p.o.) significantly shortened the escape latency times that were increased by scopolamine on the 4th day of trial sessions in the Morris water maze task. In addition, it exerted longer step-through latency times than those of the scopolamine-treated group in the passive avoidance test. Furthermore, the neuroprotective effects of fermented C. lanceolata extract on glutamate-induced neurocytotoxicity were investigated in HT22 cells. Fermented C. lanceolata extract showed a relative protection ratio of 59.62% at 500/Μg/mL. In conclusion, fermented C. lanceolata extract ameliorated scopolamine-induced memory impairments, exerted neuroprotective effects, and improved activity compared to that found with original C. lanceolata. Further study will be required to investigate the mechanisms underlying this cognitive-enhancing activity. [ABSTRACT FROM AUTHOR]

Marine microalga, Scenedesmus sp., which is known to be suitable for biodiesel production because of its high lipid content, was subjected to the conventional Folchmethod of lipid extraction combined with high-pressure homogenization pretreatment process at 1200 psi and 35?C. Algal lipid yield was about 24.9% through this process, whereas only 19.8% lipid can be obtained by following a conventional lipid extraction procedure using the solvent, chloroform: methanol (2 : 1, v/v). Present approach requires 30 min process time and a moderate working temperature of 35?C as compared to the conventional extraction method which usually requires >5 hrs and 65?C temperature. It was found that this combined extraction process followed second-order reaction kinetics, which means most of the cellular lipids were extracted during initial periods of extraction, mostly within 30 min. In contrast, during the conventional extraction process, the cellular lipids were slowly and continuously extracted for >5 hrs by following first-order kinetics. Confocal and scanning electron microscopy revealed altered texture of algal biomass pretreated with highpressure homogenization. These results clearly demonstrate that the Folch method coupled with high-pressure homogenization pretreatment can easily destruct the rigid cell walls of microalgae and release the intact lipids, with minimized extraction time and temperature, both of which are essential for maintaining good quality of the lipids for biodiesel production. [ABSTRACT FROM AUTHOR]

Marine microalga, Scenedesmus sp., which is known to be suitable for biodiesel production because of its high lipid content, was subjected to the conventional Folchmethod of lipid extraction combined with high-pressure homogenization pretreatment process at 1200 psi and 35?C. Algal lipid yield was about 24.9% through this process, whereas only 19.8% lipid can be obtained by following a conventional lipid extraction procedure using the solvent, chloroform: methanol (2 : 1, v/v). Present approach requires 30 min process time and a moderate working temperature of 35?C as compared to the conventional extraction method which usually requires >5 hrs and 65?C temperature. It was found that this combined extraction process followed second-order reaction kinetics, which means most of the cellular lipids were extracted during initial periods of extraction, mostly within 30 min. In contrast, during the conventional extraction process, the cellular lipids were slowly and continuously extracted for >5 hrs by following first-order kinetics. Confocal and scanning electron microscopy revealed altered texture of algal biomass pretreated with highpressure homogenization. These results clearly demonstrate that the Folch method coupled with high-pressure homogenization pretreatment can easily destruct the rigid cell walls of microalgae and release the intact lipids, with minimized extraction time and temperature, both of which are essential for maintaining good quality of the lipids for biodiesel production. [ABSTRACT FROM AUTHOR]

This work was to investigate the effect of flavonoids from Angelica gigas Nakai on the proliferation and differentiation of PC12 cells. Several solvents including hexane, chloroform, ethyl acetate, butanol and water consecutively partitioned. We determined the ethanol crude extract of Angelica gigas Nakai. The hexane fraction was shown to contain the highest number of flavonoids as follows; 21.48 mg/g and the composition of the flavonoids was as follows: 12.24 mg/g of quercetin, 4.39 mg/g of myricetin and 2.58 mg/g of catechin. In addition, this hexane fraction greatly increased both cell growth and outgrowth of the neurite, and whose effects were three times higher than those of the other fractions. The length of the neurites was measured as ca. 110 μm in adding 50 μg/mL of the hexane fraction, which was about the same as the case of adding 50 ng/mL of NGF as a positive control. This result indicates that the differentiation of PC12 cells by the addition of the hexane fraction was comparable to the case of adding NGF. The hexane fraction was also determined to prevent apoptosis of PC12 cells by suppressing DNA fragmentation. It is interesting that the mixture of three major flavonoids, quercetin, myricetin and catechin showed stronger activity on, both PC12 cell growth and neuritis outgrowth, than when adding each flavonoid alone. We believe this was due to the synergistic effects of the three flavonoids. The activities of these flavonoids from Angelica gigas Nakai are reported for the first time in this study. [ABSTRACT FROM AUTHOR]

We investigate the effect of self-assembled dipole molecules (SADMs) on ZnO surface in hybrid organic-inorganic polymeric light-emitting diodes (HyPLEDs). Despite the SADM being extremely thin, the magnitude and orientation of SADM dipole moment effectively influenced the work function of the ZnO. As a consequence, the charge injection barrier between the conduction band of the ZnO and the lowest unoccupied molecular orbital of poly(9,9′-dioctylfluorene)-co-benzothiadiazole could be efficiently controlled resulting that electron injection efficiency is remarkably enhanced. The HyPLEDs modified with a negative dipolar SADM exhibited enhanced device performances, which correspond to approximately a fourfold compared to those of unmodified HyPLEDs. [ABSTRACT FROM AUTHOR]

We report that adding a thin (∼10 nm) semiconducting polymer interlayer between apoly(styrenesulphonate)-doped poly(3,4-ethylenedioxythiophene) (PEDT:PSS) hole transporter and an emissive semiconductor significantly improves the device efficiency of polymer light-emitting diodes (LEDs). With the interlayer, the external quantum efficiency (EQE) increases from 0.7%(0.4 cd/A at 3.7 V) to 1.9% (1.0 cd/A at 3.3 V) at 100 cd/m2 for red LEDs and from 1.9%(6.2 cd/A at 3.4 V) to 3.0% (10.1 cd/A at 3.0 V) at 1000 cd/m2 for green LEDs. An EQE of 4.0% is also observed in blue LEDs (35% increase). The interlayer is spin-coated directly on top of the PEDT:PSS layer from a poly(2,7-(9,9-di-n-octylfluorene)-alt-(1,4-phenylene-((4-sec-butylphenyl)imino)-1,4-phenylene)) (TFB) solution. This interlayer prevents significant quenching of radiative excitons at the PEDT:PSS interface by acting as an efficient exciton blocking layer. [ABSTRACT FROM AUTHOR]

Raman spectroscopy has emerged as a powerful and important characterisation tool for probing molecular semiconducting materials. The useful optoelectronic properties of these materials arise from the delocalised π-electron density in the conjugated core of the molecule, which also results in large Raman scattering cross-sections and a strong coupling between its electronic states and vibrational modes. For this reason, Raman spectroscopy offers a unique insight into the properties of molecular semiconductors, including: chemical structure, molecular conformation, molecular orientation, and fundamental photo- and electro-chemical processes—all of which are critically important to the performance of a wide range of optical and electronic organic semiconductor devices. Experimentally, Raman spectroscopy is non-intrusive, non-destructive, and requires no special sample preparation, and so is suitable for a wide range of in situ measurements, which are particularly relevant to issues of thermal and photochemical stability. Here we review the development of the family of Raman spectroscopic techniques, which have been applied to the study of conjugated molecular semiconductors. We consider the suitability of each technique for particular circumstances, and the unique insights it can offer, with a particular focus on the significance of these measurements for the continuing development of stable, high performance organic electronic devices. [ABSTRACT FROM AUTHOR]