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Notions of decadence, decline, and decay are intrinsically linked to the history of art. The discipline’s three recognized forefathers ? Giorgio Vasari, Johann Joachim Winckelmann, and Heinrich Wölfflin ? all relied on the concept of decadence (and its antonym, progress) to make sense of the history of the visual arts and to evaluate the art of their times. A developmental model of art was central to the interpretative schemes of these art historians. In this organicist model, earlier developments prepare the stage for what comes later; and after a particular style flourishes for a time, its decline is inevitable as newer styles overtake it. Decadent artists such as Gustave Moreau and Aubrey Beardsley mock aesthetic standards and moral rules, precluding universal appreciation, and proudly so. Decadent artists and decadent audiences are estranged from their society and feel disdain for those who are scandalized by decadent art’s innovative form and immoral subject matter.
In the nineteenth century, the concept of decadence was not solely of aesthetic interest but had a number of scientific applications. Decadence itself is an organic metaphor, extending the natural processes of decline and decay to societies and the arts. Rather than rejecting nature outright, decadent authors readily embraced new scientific theories that changed the way people thought about the natural world. The pessimism of nineteenth-century science stemmed from the brutal world of industrial capitalism in which it was developed. Decadent writers then incorporated both scientific ideas and language into a literary style obsessed with decay and decline. Finally, science returned to decadent literature to pathologize certain modes of artistic expression as yet another sign that certain types of individuals were ‘degenerate’. Three key scientific theories of the nineteenth century underpin the decadent fixation on decline, decay, and degeneration: uniformitarianism, evolution, and the conservation of energy. All three theories identify impermanence in natural structures previously believed to be permanent and stable.
Polymeric conjugated materials are very promising for developing future soft material-based semiconductors, conductors, electronic and optoelectronic devices due to their inherent advantages such as flexibility, low-cost, ease of processability, and decreased harmful waste. Like their inorganic counterparts, the addition of certain dopants can significantly alter the electronic and optoelectronic properties of the host conjugated polymers or composites allowing modification for a variety of electronic/optoelectronic applications. One way to improve device performance is through the process of thermal annealing. Annealing allows for polymer matrices to self-assemble into a lower energy state which typically leads to increased crystallinity and higher charge mobility. In this work, we plan to evaluate the effects of annealing on doped P3HT films to understand its effects on optoelectronic and electronic properties focusing solely on crystallinity and charge carriers. Further understanding of the connection between annealing and doping in polymeric conjugated materials and thermoelectric properties will allow for an increase net output from multi-function materials and devices.
Organic light emitting diodes (OLEDs) have drawn great attention owing to their potential applications in high-quality flat display panels and smart solid-state lighting. Over the last three decades, numerous approaches have been made on material design and device physics to achieve high-efficiency and long-lifespan. Herein, we report a novel tactic to employ solution-processed hybrid metal oxide, molybdenum trioxide-tungsten trioxide (MoO3:WO3), as an efficient and stable hole injection/transport (HIL/HTL) and electron blocking layer for efficient OLEDs. By using phosphorescent orange-red emitter tris(2-phenylquinoline)-iridium(III) Ir(2-phq)3, MoO3:WO3 HIL based OLED device exhibits a power efficiency of 27.7 lm W-1 and 22.9 lm W-1 at 100 and 1000 cd m-2, respectively, which are 89% and 157% higher than that of conventional OLED device consisting of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as an HIL. Moreover, the resulted device also displays 1.6 times lower turn-on voltage and 3.0 time higher brightness as compare to other counter part. The higher device performances of OLED device may be attributed to robust hole transporting ability, balanced charge carrier in the recombination zone and non-acidic nature of designed HIL. Our results demonstrate that a novel alternative approach based on transition metal oxide hybrid HIL/HTL as a substitute to PEDOT:PSS for high-efficiency solution process OLEDs.
Hybrid organic-inorganic semiconducting interfaces have attracted attention in photodiodes and field-effect transistors (FETs) due to the realization of intrinsic p-n junctions and their mechanical flexibility. With the difficulty of developing high-mobility n-type organic semiconductors due to the necessity of low LUMO levels and ambient environment stability, solution processable inorganic materials are an excellent alternative. ZnO is an intrinsic n-type semiconductor which is non-toxic and sol-gel processable, creating avenues for film patterning and fully solution processed devices. We report the improvement of electron mobilities in ZnO FETs through simple UV-Ozone processing which reduces lattice defects within the film and at the SiO2/ZnO interface. Treated ZnO films yield electron mobilities close to 10-2 cm2/Vs and on/off current ratios of 104 while non-treated films have mobilities on the order of 10-5 cm2/Vs and an order of magnitude lower on/off current ratios. Treated films also yield improved photoresponsivity and detectivity in hybrid ZnO-organic photodetectors.
Consumption of cow’s milk, which is associated with diet and health benefits, has decreased in the USA. The simultaneous increase in demand for more costly organic milk suggests consumer concern about exposure to production-related contaminants may be contributing to this decline. We sought to determine if contaminant levels differ by the production method used.
Half-gallon containers of organic and conventional milk (four each) were collected by volunteers in each of nine US regions and shipped on ice for analysis. Pesticide, antibiotic and hormone (bovine growth hormone (bGH), bGH-associated insulin-like growth factor 1 (IGF-1)) residues were measured using liquid or gas chromatography coupled to mass or tandem mass spectrometry. Levels were compared against established federal limits and by production method.
Laboratory analysis of retail milk samples.
Current-use pesticides (5/15 tested) and antibiotics (5/13 tested) were detected in several conventional (26–60 %; n 35) but not in organic (n 34) samples. Among the conventional samples, residue levels exceeded federal limits for amoxicillin in one sample (3 %) and in multiple samples for sulfamethazine (37 %) and sulfathiazole (26 %). Median bGH and IGF-1 concentrations in conventional milk were 9·8 and 3·5 ng/ml, respectively, twenty and three times that in organic samples (P < 0·0001).
Current-use antibiotics and pesticides were undetectable in organic but prevalent in conventionally produced milk samples, with multiple samples exceeding federal limits. Higher bGH and IGF-1 levels in conventional milk suggest the presence of synthetic growth hormone. Further research is needed to understand the impact of these differences, if any, on consumers.
Organic light-emitting diodes (OLEDs) have attracted huge concern because of their intrinsic characteristics and ability to reach the pinnacle in the field of high-quality flat-panel displays and energy-efficient solid-state lighting. High-efficiency is always a key crux for OLED devices being energy-saving and longer life-span. OLEDs have encountered enormous difficulties in meeting the requirements for large-sized devices due to a major limitation in vacuum thermal evaporation technology. In multilayered OLED devices, the characteristics of the charge injection/transport layer is a crucial factor for the operating-voltage, power-efficiency and stability of the device. Transition metal oxides have shown great potential owing to their wide range of possible energy level alignments, balanced charge injection, and improvement of carrier mobilities. In this study, we report a solution-processed blend V2O5-PEDOT:PSS hole-injection/hole-transport layer (HIL/HTL) for efficient orange phosphorescent OLEDs. The electroluminescent characteristics of blend V2O5-PEDOT:PSS based devices were studied with the structure ITO/V2O5-PEDOT:PSS/CBP:Ir(2-phq)3/TPBi/LiF/Al. The V2O5-PEDOT:PSS based OLEDs displayed relatively higher device performance and low roll-off than that of the counter PEDOT:PSS device in terms of a maximum luminance of 17,670 cd m-2, power efficiency of 19.4 lm W-1, external quantum efficiency of 8.7%, and more importantly, low turn-on voltage. These results demonstrate an alternative approach based on metal oxide/organic blend HIL/HTL as a substitute of PEDOT:PSS for high-efficiency solution process OLEDs.
Polymeric conjugated materials are convenient for developing future soft-material-based semiconductors, conductors, electronic and optoelectronic devices due to their inherent features. Similar to their inorganic counterparts, the addition of certain minority molecules, or dopants, to polymeric conjugated materials can significantly alter the electronic and optoelectronic properties of the host conjugated polymers or composites. This allows for tunability of a variety of electronic and optoelectronic applications. One way to improve device performance is through the process of thermal annealing. Annealing allows for a polymer matrix to self-assemble into a lower energy state, which leads to an increase in crystallinity and higher charge mobility. Previous research does not explicitly define how dopants can affect this process. This study involves an evaluation of the effects of annealing with doped P3HT films to demonstrate changes in optoelectronic and electronic properties.
We present a study of optical and electronic properties of solutions and films based on the fungi-derived pigment xylindein, extracted from decaying wood and processed without and with a simple purification step (“ethanol wash”). The “post-wash” xylindein solutions exhibited considerably lower absorption in the ultraviolet spectral range and dramatically reduced photoluminescence below 600 nm, due to removal of contaminants most likely to be fungal secondary metabolites. The “post-wash” xylindein-based films were characterized by two orders of magnitude higher charge carrier mobilities as compared to “pre-wash” samples. This underlines the importance of minimizing contaminants that disrupt the conductive xylindein network in xylindein-based electronic devices.
Two benzodifuran (BDF) polymers, PBDF-C and PBDF-S, with alkyl and alkylthio substituted thiophene side-chains and benzodithiophene-4,8-dione (BDD) as the acceptor were designed and synthesized. Their optical, electrochemical properties and photovoltaic performances were systematically investigated. The polymer solar cells (PSCs) with a device structure of ITO/PEDOT:PSS/polymer:PC71BM/Ca/Al were fabricated. The PBDF-C based device showed a power conversion efficiency (PCE) of 3.01% after adding 1 vol% 1,8-diodooctane (DIO) as the solvent additive, and PBDF-S gave an enhanced PCE of 3.48% without any post-treatments. The enhancements were from the higher open-circuit voltage (Voc) and fill factor (FF). The thermal- and solvent-treatment-free processing is more favourable for the large area roll-to-roll manufacturing or printing technology for PSCs.
The surface plasmon enhanced transmission of light though a plasmonic crystal provides a novel approach for fabricating an optical modulator. The extraordinary transmission passing though these patterned metallic films is very sensitive to the surface dielectric environment. In this study, hexagonal lattice plasmonic crystals were fabricated with a self-assembly technique. Arrays of gold nano-holes or bumps with 500/600 nm periodicity were used to test the sensitivity of plasmon resonance wavelength for liquids and polymers with different dielectric constants. A nonlinear optical polymer P3HT coated onto the plasmonic crystal and pumped with 475 nm laser was found to modulate the transmission of a normally incident red light at 670 nm.
As the global energy and environmental preservation needs continue to grow, the demand for renewable and clean energy conversion materials and devices continues to rise as well. Thermoelectric (TE) materials and devices can convert waste heat into electricity and therefore it can be a potential renewable and clean energy source. Organic and polymeric materials typically exhibit low electrical conductivities, high Seebeck coefficients, and orders of magnitude lower thermal conductivities as compared to their inorganic counterparts. However, the electrical conductivities of organic/polymeric materials are tunable via doping or molecular engineering. In this study, a series of carefully doped P3HT composites are systematically evaluated for heat as well as light modulated devices. Along with a high absorption coefficient, when the polymer film thickness is less than the penetration depth of the incoming photons, the photo effects are significant and could be very useful for light modulations of thermoelectric functions. With further systematic studies and a better understanding of the mechanisms behind the photo-Seebeck effect, the development of potential high-efficiency multi-function materials and devices appears feasible.
Large area lighting OLEDs manufactured in a Roll-to-Roll (R2R) fashion enable the well-longed production capability with considerably high throughput based on flexible substrates, hence largely reduced OLED manufacturing cost. This paper will outline the present status of R2R OLED fabrication on ultra-thin glass with the focus on transparent OLED devices and how to perform segmentation by printing of silver- and dielectric pastes. Ultra-thin glass (UTG) is laminated on a PET film to avoid fabrication interruptions when glass cracks occur during the Roll-to-Roll process. The R2R fabricated flexible OLEDs also show key-values comparable to conventional OLEDs fabricated on small rigid glass in lab-scale.
The realization of an electrically driven organic solid-state laser is an ambitious but highly desirable goal. Many obstacles need to be solved before a working device can be realized. One of the most challenging tasks is an incorporation of intracavity metal contacts, which, on the one hand, would not substantially degrade optical properties of the whole device and, on the other hand, would ensure sufficient current density to reach lasing. In this paper, we present different contact compositions aiming to realize high-quality intracavity metal contacts. We build a top contact consisting of 0.5 nm of aluminum and 4 nm of silver which has a conductivity of 1.9 × 107 (Ω/m) and is not increasing the optical lasing threshold of an organic microcavity. To get a better understanding of charge carriers influencing the device performance, we have performed a set of measurements, where a hybrid OLED–MC device was excited both optically and electrically at the same time. These experiments suggest that the charge carriers do not degrade electrical performance, at least for current densities in the range of A/cm2. Moreover, our observations suggest that, in some cases, simultaneous optical excitation can contribute to more efficient electrical pumping of the OLED-MC device.
One-dimensional hybrid Distributed Bragg Reflector (DBR) is constructed using Tris (8-hydroxy) quinoline aluminum (Alq3) molecules and Titanium dioxide (TiO2) nanoparticles via spin coating process. Light emission from thin films of low molecular weight organic semiconductor of Alq3 is dominated by excitons. This material has been widely used as a superior emitter for organic light emitting diodes. Titanium dioxide (TiO2) is an inorganic semiconductor with a high band gap. Photoluminescence (PL) of thin films of Alq3 showed a broad PL peak at 530 nm. In DBR structures, PL quenching is observed but there is no shift in the PL peak of the Alq3. The PL quenching is tentatively attributed to energy transfer via sensitization to wide band gap TiO2 layers. A simple excitonic model is suggested to explain the observation. Fabrication process and optical properties of the structure are presented.
Weeds have acquired evolutionary adaptations to the diverse crop and weed management strategies used in cropping systems. Therefore, changes in crop production practices such as conventional to organic systems, tillage-based to no-till systems, and diversity in crop rotations can result in differences in weed community composition that have management implications. A study was carried out to understand the weed community dynamics in a long-term alternative cropping systems study at Scott, SK, Canada. Long-term (18-yr) weed community composition data in wheat (Triticum aestivum L.) in ORG (organic), RED (reduced-input, no-till), and HIGH (high-input, conventional tillage) systems with three levels of crop rotation diversity, LOW (low diversity), DAG (diversified annual grains), and DAP (diversified annuals and perennials), were used to study the effect of different cropping systems and the effect of environment (random temporal effects) on residual weed community composition using the principal response curve (PRC) technique. The interaction between cropping systems and year-to-year random environmental changes was found to be the predominant factor causing fluctuations in weed community composition. Furthermore, the single most predominant factor influencing the weed composition was year-to-year random changes. Organic systems clearly differed from the two conventional systems in most years and had more diverse weed communities compared with the two conventional systems. The two conventional systems exhibited similar weed composition in most years. In this study, the use of the PRC method allowed capture of the real temporal dynamics reflected in the cropping systems by time interaction. This study further concludes that moving from a tillage-based, high-input conventional system to a no-till, reduced-input system did not cause significant changes in the weed community composition throughout the time period, but diversity in organic systems was high, probably due to increased occurrence of some difficult to control species.
Piglet mortality in outdoor production systems varies across the year, and a reason for this variation could be fluctuations in hut climate, as ambient temperature might influence piglet survival, both directly and indirectly. Therefore, the aim of the current study was to investigate the impact of farrowing hut climate and year variation on stillbirth and liveborn mortality. A large-scale observational study was conducted at five commercial organic pig-producing herds in Denmark from June 2015 to August 2016. Both year variation (F3,635=4.40, P=0.004) and farrowing hut temperature (F2,511=6.46, P=0.002) affected the rate of stillbirths. The risk of stillborn piglets was lowest in winter and during this season larger changes in hut temperature between day 1 prepartum and the day of farrowing increased the risk of stillbirths (F1,99=6.39, P=0.013). In addition, during the warm part of the year stillbirth rate increased at temperatures ⩾27°C. Year variation also affected liveborn mortality (F3,561=3.86, P=0.009) with a lower rate of liveborn deaths in spring. However, the hut climate did not influence liveborn deaths. Consequently, other factors than hut climate may explain the influence of year variation on liveborn mortality. These could be light differences causing seasonality in reproduction and lactation.
We investigate the photostability of a set of organic semiconductor blends comprising a conjugated polymer as the donor and a fullerene as the acceptor using electron spin resonance (ESR). In the absence of oxygen, all blends show excellent stability. Even after several hundred hours of exposure to solar or UV radiation, the ESR spectra and the recombination of photoinduced charges recorded at low temperature are found to be unchanged. By contrast, the presence of oxygen leads to a fast light-induced degradation rendering the ability of the donor/acceptor system to form photoinduced charge carriers. Our findings suggest that conjugated polymer–fullerene blends exhibit very good photostability and that oxygen needs to be excluded in optoelectronic applications. Our findings also suggest that at low temperature, a universal recombination process of long-lived photoinduced charges is active, which does not depend on the electronic structure or the morphology of the investigated materials.
Thin hole transport layers are important elements in organic semiconductor-based devices. Metal oxides are an encouraging material class for this purpose, as they may provide sufficient hole conduction in combination with excellent electron blocking properties. Both, long-term device stability, which may often be limited by the thermal stability of interfaces, and higher temperature processing steps, benefit strongly from the existence of thermally stable metal oxide interlayers. Provided that thermally stable electrodes can be fashioned, the stability of organic active layers—for example, in organic field effect transistors, light emitting diodes, or photovoltaic (OPV) devices can be investigated. Here, we apply this concept and report about the study of hole mobility (µh) in single-carrier-hole-only devices in dependence of thermal annealing up to the above the actual melting temperature of regio-regular poly(3-hexylthiophene-2,5-diyl) (P3HT).
7-Decyl-2-phenylbenzothieno[3,2-b]benzothiophene (Ph-BTBT-C10) is a soluble organic semiconductor that can afford high mobility organic thin-film transistors (OTFTs). The material exhibits inherent high layered crystallinity due to the formation of bilayer-type layered-herringbone packing that involves nearly independent π-electron core layers and alkyl-chain layers within the crystals. Here, we discuss that the bottom-gate/top-contact OTFTs composed of single-crystalline Ph-BTBT-C10 channel layers exhibit noticeable effects in the device characteristics caused by the highly insulating nature of the alkyl-chain layers. Notable layer-number (n) dependence was observed in the nonlinear current–voltage characteristics and the device mobility (2–14 cm2/Vs, with TFT ideality factor 15–46%, mainly due to large threshold voltages), which can be clearly ascribed to the tunneling-based interlayer access resistance across the alkyl-chain layers. The gated-four-probe measurements of single-crystalline OTFTs also revealed quite high mobility more than 40 cm2/Vs along the channel semiconducting layer, whereas highly insulating effects due to the alkyl-chain layers were also apparent as the large hysteresis in the gate-off states of OTFTs. We discuss the whole features of the tunneling-based access resistance in the device operations of single-crystalline OTFTs, on the basis of comparison between experimental results and model simulations.