Merck Serono Ltd. (United Kingdom)

Today, Fmoc SPPS is the method of choice for peptide synthesis. Very-high-quality Fmoc building blocks are available at low cost because of the economies of scale arising from current multiton production of therapeutic peptides by Fmoc SPPS. Many modified derivatives are commercially available as Fmoc building blocks, making synthetic access to a broad range of peptide derivatives straightforward. The number of synthetic peptides entering clinical trials has grown continuously over the last decade, and recent advances in the Fmoc SPPS technology are a response to the growing demand from medicinal chemistry and pharmacology. Improvements are being continually reported for peptide quality, synthesis time and novel synthetic targets. Topical peptide research has contributed to a continuous improvement and expansion of Fmoc SPPS applications.

We report herein a comparison of the photophysics of a series of polythiophenes with ionization potentials ranging from 4.8 to 5.6 eV as pristine films and when blended with 5 wt % 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]C61 (PCBM). Three polymers are observed to give amorphous films, attributed to a nonplanar geometry of their backbone while the other five polymers, including poly(3-hexylthiophene), give more crystalline films. Optical excitation of the pristine films of the amorphous polymers is observed by transient absorption spectroscopy to give rise to polymer triplet formation. For the more crystalline pristine polymers, no triplet formation is observed, but rather a short-lived (approximately 100 ns), broad photoinduced absorption feature assigned to polymer polarons. For all polymers, the addition of 5 wt % PCBM resulted in 70-90% quenching of polymer photoluminescence (PL), indicative of efficient quenching of polythiophene excitons. Remarkably, despite this efficient exciton quenching, the yield of dissociated polymer+ and PCBM- polarons, assayed by the appearance of a long-lived, power-law decay phase assigned to bimolecular recombination of these polarons, was observed to vary by over 2 orders of magnitude depending upon the polymer employed. In addition to this power-law decay phase, the blend films exhibited short-lived decays assigned, for the amorphous polymers, to neutral triplet states generated by geminate recombination of bound radical pairs and, for the more crystalline polymers, to the direct observation of the geminate recombination of these bound radical pairs to ground. These observations are discussed in terms of a two-step kinetic model for charge generation in polythiophene/PCBM blend films analogous to that reported to explain the observation of exciplex-like emission in poly(p-phenylenevinylene)-based blend films. Remarkably, we find an excellent correlation between the free energy difference for charge separation (deltaG(CS)rel) and yield of the long-lived charge generation, with efficient charge generation requiring a much larger deltaG(CS)rel than that required to achieve efficient PL quenching. We suggest that this observation is consistent with a model where the excess thermal energy of the initially formed polaron pairs is necessary to overcome their Coulombic binding energy. This observation has important implications for synthetic strategies to optimize organic solar cell performance, as it implies that, at least devices based on polythiophene/PCBM blend films, a large deltaG(CS)rel (or LUMO level offset) is required to achieve efficient charge dissociation.

Abstract Organic semiconductors are emerging as a viable alternative to amorphous silicon in a range of thin‐film transistor devices. With the possibility to formulate these p‐type materials as inks and subsequently print into patterned devices, organic‐based transistors offer significant commercial advantages for manufacture, with initial applications such as low performance displays and simple logic being envisaged. Previous limitations of both air stability and electrical performance are now being overcome with a range of both small molecule and polymer‐based solution‐processable materials, which achieve charge carrier mobilities in excess of 0.5 cm 2 V −1 s −1 , a benchmark value for amorphous silicon semiconductors. Polymer semiconductors based on thienothiophene copolymers have achieved amongst the highest charge carrier mobilities in solution‐processed transistor devices. In this Progress Report, we evaluate the advances and limitations of this class of polymer in transistor devices.

This work describes a new design methodology that allows the preparation of air stable, semiconducting thiophene polymers with high charge carrier mobilities. The incorporation of thieno[2,3-b]thiophene into a polythiophene backbone introduces cross-conjugated double bonds that disfavor full delocalization, leading to high ionization potential in comparison to a fully conjugated polythiophene, with no reduction in charge carrier mobility. The resulting solution processable polymers exhibit charge carrier mobilities up to 0.15 cm2/V s and on/off ratios greater than 105 when measured in air. Transistors exhibit lifetimes of several months in air with no encapsulation necessary.

High performance, solution processable semiconductors are critical to the realization of low cost, large area electronics. We show that a signature molecular packing motifside-chain interdigitationcorrelates to high performance for a large and important class of organic semiconductors. The side chains of recently developed high performance copolymers of poly(alkylthiophenes) can and do interdigitate substantially, whereas they do not in the most common form of the extensively studied, lower performance poly(alkythiophenes). Side-chain interdigitation provides a mechanism for three-dimensional ordering; without it, poly(alkylthiophenes) are limited to small domains and poor performance. We propose the synthetic design rule that three-dimensional ordering is promoted by side-chain attachment densities sufficiently low to permit interdigitation.

The synthesis of regioregular poly(3-hexyl)selenophene is reported, and its optical and electrical properties are compared to those of regioregular poly(3-hexyl)thiophene.

Three G protein-coupled receptors (Edg-1, Edg-3, and Edg-5) for the lysolipid phosphoric acid mediator sphingosine 1-phosphate have been described by molecular cloning. Using a similar sequence that we found in the expressed sequence tag data base, we cloned and characterized of a fourth, high affinity, rat brain sphingosine 1-phosphate receptor, Edg-8. When HEK293T cells were co-transfected with Edg-8 and G protein DNAs, prepared membranes showed sphingosine 1- phosphate-dependent increases in [(35)S]guanosine 5'-(3-O-thio)triphosphate binding with an EC(50) of 90 nm. In a rat hepatoma Rh7777 cell line that exhibits modest endogenous responses to sphingosine 1-phosphate, this lipid mediator inhibited forskolin-driven rises in cAMP by greater than 90% when the cells were transfected with Edg-8 DNA (IC(50) 0.7 nm). This response is blocked fully by prior treatment of cultures with pertussis toxin, thus implicating signaling through G(i/o)alpha proteins. Furthermore, Xenopus oocytes exhibit a calcium response to sphingosine 1-phosphate after injection of Edg-8 mRNA, but only when oocytes are co-injected with chimeric G(q/i)alpha protein mRNA. Membranes from HEK293T and Rh7777 cell cultures expressing Edg-8 exhibited high affinity (K(D) = 2 nm) binding for radiolabeled sphingosine 1-phosphate. Rat Edg-8 RNA is expressed in spleen and throughout adult rat brain where in situ hybridization revealed it to be associated with white matter. Together our data demonstrate that Edg-8 is a high affinity sphingosine 1-phosphate receptor that couples to G(i/o)alpha proteins and is expressed predominantly by oligodendrocytes and/or fibrous astrocytes in the rat brain.

The structure within crystalline thin films of a high-carrier-mobility polythiophene is studied with complementary characterization methods and first-principles theory. As shown in the figure, two important structural aspects are revealed: 1) a slip in the face-to-face π-π packing, which strongly influences carrier mobility, and 2) the interdigitation of highly trans side chains between vertically adjacent lamellae.

Inline printing and coating methods have been demonstrated to enable a high technical yield of fully roll-to-roll processed polymer tandem solar cell modules. We demonstrate generality by employing different material sets and also describe how the ink systems must be carefully co-developed in order to reach the ambitious objective of a fully printed and coated 14-layer flexible tandem solar cell stack. The roll-to-roll methodologies involved are flexographic printing, rotary screen printing, slot-die coating, X-ray scattering, electrical testing and UV-lamination. Their combination enables the manufacture of completely functional devices in exceptionally high yields. Critical to the ink and process development is a carefully chosen technology transfer to industry method where first a roll coater is employed enabling contactless stack build up, followed by a small roll-to-roll coater fitted to an X-ray machine enabling in situ studies of wet ink deposition and drying mechanisms, ultimately elucidating how a robust inline processed recombination layer is key to a high technical yield. Finally, the transfer to full roll-to-roll processing is demonstrated.

Interchain interactions have a profound effect on the optical as well as charge transport properties of conjugated polymer thin films. In contrast to oligomeric model systems in solution-deposited polymer thin films the study of such effects is complicated by the complex microstructure. We present here a detailed study of interchain interaction effects on both charged polarons as well as neutral excitons in highly crystalline, high-mobility poly-3-hexylthiophene (P3HT) as a function of molecular weight. We find experimental evidence for reduced exciton bandwidth and increased polaron delocalization with increasing conjugation length and crystalline quality. From comparative studies of field-effect transistor characteristics, film morphology, and optical properties our study provides a microscopic understanding of the factors which limit the charge transport in P3HT to field-effect mobilities around $0.1\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}∕\mathrm{V}\phantom{\rule{0.2em}{0ex}}\mathrm{s}$, and which will need to be addressed to improve mobility further.

Abstract The time‐of‐flight method has been used to study the effect of P3HT molecular weight ( M n = 13–121 kDa) on charge mobility in pristine and PCBM blend films using highly regioregular P3HT. Hole mobility was observed to remain constant at 10 −4 cm 2 V −1 s −1 as molecular weight was increased from 13–18 kDa, but then decreased by one order of magnitude as molecular weight was further increased from 34–121 kDa. The decrease in charge mobility observed in blend films is accompanied by a change in surface morphology, and leads to a decrease in the performance of photovoltaic devices made from these blend films.

The technology behind a large area array of flexible solar cells with a unique design and semitransparent blue appearance is presented. These modules are implemented in a solar tree installation at the German pavilion in the EXPO2015 in Milan/IT. The modules show power conversion efficiencies of 4.5% and are produced exclusively using standard printing techniques for large-scale production. In this Communication, we present the technology behind the solar tree installation at the German pavilion, Milan EXPO, which represents a paradigm shift in solar technology, as it incorporates a large area array of flexible solar cells with a unique design and semitransparent blue appearance. The modules show power conversion efficiencies of 4.5% and were produced exclusively using common printing techniques. High performance organic photovoltaic (OPV) polymers have been recently reported in the literature, highlighting the potential of carbon-based semiconductors as a realistic source of power generation. OPV modules have the potential for extremely fast payback times for both energy, carbon, and cost versus other solar technologies.1-3 In terms of absolute device performance, 3rd Gen PV technologies are lagging behind approaches based on Si, CIGS, etc., but offer inherent advantages in flexibility, form factors, colour, transparency, lightweight, indoor efficiency, low-light efficiency, and off-axis performance. In the case of building integrated PV (BIPV), the inherent freedom of design and versatile adaptability allows OPV to better serve functional and aesthetic demands from architects as compared to classic PV technologies. Examples are the unique choice of colours, shapes, and degrees of transparency, which strongly improves the prospects to comply with preferred façade designs, and the straightforward compatibility with upcoming membrane architecture due to its flexible nature.4 Approaching the production of modules via solution-based polymers also opens up cost-effective and scalable roll-to-roll (R2R) manufacturing techniques with low environmental impact.5, 6 PBTZT-stat-BDTT-8 addresses many of the current technical challenges toward the commercialization of OPV that have been recently outlined9, 10 and offers a real alternative to P3HT. From a materials standpoint, PBTZT-stat-BDTT-8 can offer up to 9% PCE on the cell level, establishing it as a top tier OPV polymer along with the PTB7 family,11-13 the PBDTBDD and PDBT-T1 family,14, 15 the PPDT2FBT family,16 the PffBT4T-2OD family,17 and recently DT-PDPP2T-TT.18 Most importantly, state-of-the-art progress from lab cell to fully R2R modules producing 4.5% power conversion efficiency (PCE) from semitransparent modules is demonstrated herein. This pioneering work has already shown the highest reported performance of flexible R2R modules of fully solution-processed single junction OPV design19, 20 leading to its first demonstration of flexible, semitransparent OPV modules integrated into the Universal EXPO in Milan, 2015.7, 8, 21 PBTZT-stat-BDTT-8 is the outcome of polymer backbone optimization from our previously reported polymer system based on the PBTZTBDTT family, and is composed of substituted benzodithiophene, thiophene, and benzothiadiazole (Figure 1b).22 The “R1” and “R2” were selected from a library of polymers and simultaneously enhances solubility, power conversion efficiency,23 and device stability.24, 25 The result is a royal-blue polymer with a band gap of 1.7 eV and absorption peaks at 600 nm and 640 nm in the solid state. The frontier molecular energy levels of PBTZT-stat-BDTT-8 were measured by cyclic voltammetry at −3.7 and −5.4 eV. The molecular weight of PBTZT-stat-BDTT-8 is used to alter formulation viscosity to match the technique requirements of a particular printing or coating method. In the present case of doctor blade and slot-die coating, the molecular distribution was fixed at Mn = 22.2 kg mol−1 (Mw = 49.5 kg mol−1, ĐM = 2.23).26 PBTZT-stat-BDTT-8 is widely soluble in common organic solvents which are used for bulk heterojunction (BHJ) processing, including 1,2-dichlorobenzene, chlorobenzene, chloroform, o-xylene, 1-methylnaphthalene, tetraline, and mesitylene, amongst others.27, 28 High PCE can be obtained by optimizing formulations in any of these solvents although we have determined that mixtures of o-xylene and tetraline provide a good balance of PCE, solubility, fullerene solubility, viscosity and coating uniformity, while being entirely halogen free.28, 29 As clearly illustrated by Krebs and Jorgensen, a true demonstration of a commercial high performance OPV polymer can only be performed on large areas, by many laboratories, and using commercially relevant printing techniques.10 Our evaluation and optimization commenced on small area cells measuring 0.04 cm2. To facilitate the transfer from a lab scale process to a R2R process, ink formulation and device optimizations were performed using a doctor blade coating technique rather than spin-coating. Here we employed solution processable PEDOT:PSS as a hole-transporting layer (HTL, Clevios P VP AL 4083), PV-E001 as an electron-transporting layer (ETL, Merck), and 1,2-dichlorobenzene as a screening solvent for the standard architecture. Combining PBTZT-stat-BDTT-8 with PC60BM (Lisicon PV-A600) in 1,2-dichlorobenzene with a solids loading of 30 mg mL−1 (1:2 weight ratio of PBTZT-stat-BDTT-8:PV-A600) allowed the fabrication of state-of-the-art regular stack OPV devices giving 9.3% PCE peak (8.5% PCE average, Figure 2). This is one of the few commercially available polymers which is currently able to produce >9% PCE using an industrially relevant coating technique, off the shelf solution processed interlayers, and PC60BM as an acceptor material. The EQE of these devices exceed 70% with a peak of 80% at 668 nm in the standard architecture. Exceptionally high FF are produced in the range of 74%–70% even at active layer thicknesses of 500 nm (Figure 3b). These performances can be consistently reproduced in our laboratory. The next stage in development was to transition to systems that would highlight any challenges of Lisicon PBTZT-stat-BDTT-8 integration into commercially viable mass-produced OPV prototypes. It was therefore essential not only to measure the effects of moving to larger active areas and to plastic substrates in view of R2R OPV processes, but also to move from dichlorobenzene to nonhalogenated solvents for the active formulation in order to satisfy the requirements for industrial mass-production. In this case, work was carried out on both device architectures, the inverted stack being fabricated by using PV-E002 as the ETL in combination with PEDOT:PSS (HTL Solar Clevios 388). We combined PBTZT-stat-BDTT-8 and PV-A600 (30 mg mL−1 and 1:1.5 weight ratio) in a mixture of tetralin (12.5 vol%) and o-xylene (87.5 vol%); the solvent mixture giving a suitable balance of solubility, performance, and viscosity.29, 30 Moving to large area devices produces additional losses from an increase in the series resistance across the cell, leading to a lowering of the performance.9, 31-33 Devices at 1.00 cm2 give peak PCEs at 7.5% (7.2% average PCE) for the inverted stack architecture. The main losses from the large area devices arise from a reduction in fill factor stemming from an increase in series resistance, for which the bottom cell design and conductivity are key contributors as highlighted by the difference between the regular and inverted stack behaviors at forward bias (Figure 2A). Inverted stack devices at 0.27 cm2 and prototyped on ITO-metal-ITO (IMI) coated PET exhibit a decrease in the overall performance driven by the Jsc compared to the equivalent device on glass (Table 1). PBTZT-stat-BDTT-8 allows thick active layers to be coated, therefore compensating for most of the optical losses of the substrates, while maintaining high FF and PCE (Figure 3B). The final stage of integration of PBTZT-stat-BDTT-8 into modules was performed using a R2R process. The substrates are made of prestructured IMI on PET, and the HTL and ETL were PEDOT:PSS HTL Solar Clevios 388 and PV-E002, respectively. The HTL was customized in order to ensure printability on top of the BHJ and its compatibility with an additional transparent conductive layer (TCL) of PEDOT:PSS PH1000, helping current extraction when used in conjunction with a Ag grid electrode. The performances were first checked on cells measuring 0.27 cm2, which were cut out of the roll of OPV modules printed by R2R and completed using evaporated Ag. In this configuration, performances of 4.8% PCE can be reached from the opaque cells. This validates the particular architecture of the OPV stack and its processing by R2R, even if some losses in performance originate from the lower Jsc values. Those losses are attributed to the high thickness of the bilayer of HTL, which reduce the contribution of the evaporated Ag electrode to the Jsc by means of multireflection processes, and which can also change the light distribution in the BHJ. Moving from an evaporated electrode to an interdigitated Ag structure, the latter being needed to attain a semitransparent final product, leads to performances as high as 4.5% PCE prior to encapsulation. Remarkably, this BELECTRIC OPV process and design minimizes losses of the Voc and FF versus lab-scale devices, despite the stack being fully printed.34-36 In real world tests, these bifacial semitransparent modules are expected to exhibit a slight increase in efficiency by harvesting light from both sides.37 The modules consist of a combination of 54 cells in total, grouped as 9 serially connected cells, which are then connected in parallel (Figure 4). A record 4.3% average PCE for the module was achieved for this semitransparent system. The use of high precision laser structuring allows the increase of the geometrical fill factor (GFF) to a high level of 95%.34-36 This contributes not only to improving the module performance, but also significantly improves the aesthetic appeal of the final modules, which is key to delivering building integrated photovoltaics (BIPV, Figure 1).38 More than 250 m2 of modules, with an average performance of 4% PCE and an average transparency of ≈20% were fabricated for installation in the solar trees at the German pavilion in the 2015 Universal Expo in Milan. Besides performance, excellent thermal stability of the OPV modules is a prerequisite for their integration into many end products. For instance OPV elements embedded in glass (e.g., façade elements) require stability for 2 h at 120 °C in the lamination process.38 Thus these conditions serve as good test standard and were carried out on inverted single cells on PET (same configuration as Type 4, Figure 3). The device was periodically measured during this test in order to track any changes in performance during thermal stress. After an initial 15 minutes of heating, an increase in Jsc is observed causing an increase in PCE while FF and Voc remain unchanged. Beyond the 60 minutes timeframe, a slow decrease in FF and Jsc result in a minor loss in PCE, reverting back to its starting performance of 5.6%. Overall excellent thermal stability is observed for PBTZT-stat-BDTT-8 in this device configuration showing no significant change over 2 h of heating, thereby allowing for its integration within laminated supports. This result is attributed to the intrinsic thermal stability of PBTZT-stat-BDTT-8, and to its incorporation into a finely tuned stack and solvent mixture. To validate the usage of the trigon modules under real conditions during the Universal EXPO in Milan 2015, light-soaking experiments of the systems were run under 1 Sun illumination without showing any significant decrease in PCE over the first 100 h. More data will be collected during the Universal EXPO and will be reported at a later stage. In the meantime, further engineering in terms of donor and acceptor materials and formulations are ongoing in order to enable any OPV market segments and printing processes with PBTZT-stat-BDTT-8. In conclusion, PBTZT-stat-BDTT-8 demonstrates a combination of features that are essential for the integration into sustainable and adaptable commercial OPV products, such as membrane architecture applications or as laminates in glass-glass elements. On the lab-scale, this material offers efficiencies higher than 9% PCE, which is comparable to the best polymers reported to date. In addition to high performance, excellent processability is also critical when moving to fully solution-based, R2R fabrication of OPV modules: PBTZT-stat-BDTT-8 is able to reach high performance with commercially viable acceptor materials, such as PC60BM and using a variety of coating technologies, broad thickness range, different cell sizes, and with formulations in a variety of nonhalogenated solvents. This unique combination of high optoelectronic performance and wide processing window enabled the fabrication of >250 m2 flexible “trigon” modules reaching an average performance of 4.3% PCE, while maintaining a high level of transparency and aesthetic appeal. In real world tests, these bifacial modules are expected to show an increase in efficiency due to light harvesting from both sides.37 Furthermore, initial tests on the thermal stability of these OPV modules meet requirements for lamination protocols for glass-based BIPV products, thereby accessing the important market of façade applications (in the context of the upcoming nearly-zero energy building directive 2010/31/EU). The large deployment of this material during the Universal EXPO 2015 in Milan is the first example of large-scale production of customized high performing solution-processable OPV systems, a clear demonstration that OPV is a viable technology to complement and contribute to the energy mix in a decarbonized global economy. Materials: PBTZT-stat-BDTT-8, PV-A600, PV-E001, and PV-E002 were purchased from Merck. ITO-patterned substrates were purchased from Zencatec. PET-based flexible substrates comprising a transparent conductive layer, namely an ITO-metal-ITO (IMI) sandwich structure, were purchased from Materion and used for R2R module fabrication. Clevios HTL Solar 388, Clevios P VP Al 4083, Clevios PH 1000, and the Ag ink used for screen-printing were purchased from Heraeus. The solvents as well as the metals to evaporate were bought through Sigma-Aldrich. Polymer Characterization: Gel permeation chromatography (GPC) was performed at an elution rate of 1 mL min−1 with 1,2,4-trichlorobenzene (Aldrich) at 160 °C through a PSS polefin 10 μm (50 × 8 mm) precolumn and three PSS polefin 10 μm (300 × 8 mm) GPC columns. The polymers were analyzed with a refractive index detector calibrated with narrow polystyrene standards. Samples were prepared at a concentration of 3 mg mL−1. Cyclic voltammograms were recorded using a Princeton Applied Research VersaSTAT 4 potentiostat. Films of the polymers were cast from a concentrated chloroform solution onto a platinum wire working electrode. Voltammograms were recorded in an anhydrous acetonitrile solution containing 0.1 M NBu4+ BF4− electrolyte with a platinum wire counter electrode and 0.1 m Ag AgNO3−1 in acetonitrile reference electrode. The solutions were purged with N2 gas and referenced to an external ferrocene solution which was also used to calculate the ionization potential (IP) and electron affinity (EA) positions (Eorbital = −(Eonset + 5.1) eV).39 OPV Cells and Modules Fabrication: All the devices at lab-scale were fabricated by doctor blade coating under ambient conditions. The only exception was the HTL in the regular stack, which was coated by spin-coating, under ambient conditions. Prepatterned substrates of IMI or ITO were cleaned with a sequence of successive baths in acetone, IPA, and distilled water. Substrates were then dried with compressed air. In the case of the small cell sizes in the regular stack architecture (0.04 cm2, type 1), the HTL made of Clevios P VP Al 4083 was filtered (PVDF coated, 0.45 μm pore size and 25 mm diameter, from Merck Millipore) and then added to distilled water in a 1:1 ratio per volume. The formulation was then coated by spin-coating at 4000 rpm for 60 s to reach a thickness of 20 nm, and annealed at 120 °C for 30 minutes in air. The active layer formulation was made by mixing PBTZT-stat-BDTT-8 with Merck PV-A600 in 1,2-dichlorobenzene with a solids loading of 30 mg mL−1 (1:2 weight ratio of PBTZT-stat-BDTT-8:PV-A600). The formulation was heated for 2 to 3 h on a hotplate at 90 °C under stirring, after which it was ready to be coated on top of the HTL. The coating parameters for the active layer formulations are: speed = 30 mm s−1, temperature = 70 °C, gap = 100 μm, volume = 70 μL. The film was dry after 2 minutes at 70 °C. The solution of PV-E001 was maintained at room temperature and a volume of 30 μL was coated on top of the BHJ by doctor blade at room temperature, with a speed of speed = 20 mm s−1, gap = 50 μm, after which a successive layer of Ag (100 nm) and Al (100 nm) were evaporated at a standard rate of 1–5 Å s−1. In the case of large cell size (100 mm2, type 2), a different solvent system was used composed of 87.5% o-xylene and 12.5% tetralin with a solids loading of 30 mg mL−1 (1:1.5 weight ratio of PBTZT-stat-BDTT-8:PV-A600). For inverted stack architecture devices (types 3 and 4), 140 μL of PV-E002 was coated by doctor blade from a formulation at room temperature at a speed of 5 mm s−1, a doctor blade temperature of 80 °C, and a gap = 575 μm, on top of the substrates. The BHJ was processed from a nonhalogenated solvent mixture as described previously and the HTL Solar 388 was coated on top by doctor blade from a formulation maintained at room temperature, with a speed of 30 mm s−1, a gap of 575 μm, and the doctor blade being at a temperature of 65 °C. An evaporation of Ag (100 nm) was then used to complete the stack. All modules were fabricated on a R2R machine as previously described.40 The machine comprises different un-winders, edge guides, backing rolls, IR heaters, impingement dryers, three slot-die heads, and one rotary screen printing unit. A camera system and a UV/VIS spectrometer were installed for quality analysis of the laser lines and coated layers. The IMI substrates, rolls of 165 mm × 150 m, were P1 structured with a Rofin 1064 nm Nd:YVO4 laser. PV-E002 was stirred for 30 minutes at room temperature, the active materials in a solvent mixture of 87.5% Xylene and 12.5% Tetralin with a solid content of 37.0 mg mL−1 (PBTZT-stat-BDTT-8:PV-A600 ratio of 1:1.5) was stirred overnight at 90 °C, and HTL Solar 388 and PH were stirred at room temperature for 2 h. PV-E002 was slot-die coated with a dry layer thickness of 5 The BHJ was coated with a heated and coating with a dry layer thickness of 250 layers were coated in one run with 2 m min−1 and additional were HTL Solar 388 and PH were coated with a dry layer thickness of 70 nm and 150 nm, in one coating run at 1 m and was laser structured with the laser and the semitransparent top electrode was screen printed from Ag ink with a dry layer of 6 The final modules were between with the use of an OPV and Characterization: The areas of the solar cells were by the area of the top electrode evaporated on top of the were checked by optical to The Jsc reported were from EQE The solar was a giving and as calibrated with a In the case of plastic devices and modules, of the solar cells and modules were recorded under a calibrated solar with 1 by using a source in combination with a system. efficiency was measured with a were performed with an were by using a This was in by the German of and Research and

The electrical instability of organic field-effect transistors is investigated. We observe that the threshold-voltage shift (see figure) shows a stretched- exponential time dependence under an applied gate bias. The activation energy of 0.6 eV is common for our and all other organic transistors reported so far. The constant activation energy supports charge trapping by residual water as the common origin.

We report on charge transport in organic field-effect transistors based on poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) as the active polymer layer with saturation field-effect mobilities as large as 1cm2V−1s−1. This is achieved by employing Pt instead of the commonly used Au as the contacting electrode and allows for a significant reduction in the metal/polymer contact resistance. The mobility increases as a function of decreasing channel length, consistent with a Poole-Frenkel model of charge transport, and reaches record mobilities of 1cm2V−1s−1 or more at channel lengths on the order of few microns in an undoped solution-processed polymer cast on an oxide gate dielectric.

A concerted commitment across research stakeholders is necessary to increase equity, diversity, and inclusion (EDI) and address barriers to cancer clinical trial recruitment and participation. Racial and ethnic diversity among trial participants is key to understanding intrinsic and extrinsic factors that may affect patient response to cancer treatments. This ASCO and Association of Community Cancer Centers (ACCC) Research Statement presents specific recommendations and strategies for the research community to improve EDI in cancer clinical trials. There are six overarching recommendations: (1) clinical trials are an integral component of high-quality cancer care, and every person with cancer should have the opportunity to participate; (2) trial sponsors and investigators should design and implement trials with a focus on reducing barriers and enhancing EDI, and work with sites to conduct trials in ways that increase participation of under-represented populations; (3) trial sponsors, researchers, and sites should form long-standing partnerships with patients, patient advocacy groups, and community leaders and groups; (4) anyone designing or conducting trials should complete recurring education, training, and evaluation to demonstrate and maintain cross-cultural competencies, mitigation of bias, effective communication, and a commitment to achieving EDI; (5) research stakeholders should invest in programs and policies that increase EDI in trials and in the research workforce; and (6) research stakeholders should collect and publish aggregate data on racial and ethnic diversity of trial participants when reporting results of trials, programs, and interventions to increase EDI. The recommendations are intended to serve as a guide for the research community to improve participation rates among people from racial and ethnic minority populations historically under-represented in cancer clinical trials. ASCO and ACCC will work at all levels to advance the recommendations in this publication.

The carrier transport of carefully purified regioregular poly(3-hexylthiophene) films has been studied using time-of-flight photocurrent measurements. We find balanced ambipolar transport with a room-temperature mobility for holes of 3×10−4cm2V−1s−1 and for electrons of 1.5×10−4cm2V−1s−1 at electric fields ⩾105V∕cm. The transport is relatively field independent and weakly temperature dependent, pointing to a high degree of chemical regioregularity and purity. These factors make poly(3-hexylthiophene) attractive for use in a range of electronic applications.

Here we report the chemical induction of the twist-bend nematic phase in a nematic mixture of ether-linked liquid crystal dimers by the addition of a dimer with methylene links; all dimers have an odd number of groups in the spacer connecting the two mesogenic groups. The twist-bend phase has been identified from its optical texture and x-ray scattering pattern as well as NMR spectroscopy, which demonstrates the phase chirality. Theory predicts that the key macroscopic property required for the stability of this chiral phase formed from achiral molecules is for the bend elastic constant to tend to be negative; in addition the twist elastic constant should be smaller than half the splay elastic constant. To test these important aspects of the prediction we have measured the bend and splay elastic constants in the nematic phase preceding the twist-bend nematic using the classic Frederiks methodology and all three elastic constants employing the dynamic light scattering approach. Our results show that, unlike the splay, the bend elastic constant is small and decreases significantly as the transition to the induced twist-bend nematic phase is approached, but then exhibits unexpected behavior prior to the phase transition.

Abstract A range of nematogenic materials which incorporate a 2,6-disubstituted naphthyl moiety and a terminal cyano-substituent have been synthesized by using palladium-catalysed cross-coupling procedures involving arylboronic acids and alkynylzinc reagents with aryl iodides, bromides and trifluoromethanesulphonates (triflates). The compounds have very high nematic phase stability, but their melting points are also quite high. The birefringences were measured using an extrapolation technique and the values were found to be between 0·26 and 0·42.

Abstract Solid‐state dye‐sensitized solar cells employing a solid organic hole‐transport material (HTM) are currently under intensive investigation, since they offer a number of practical advantages over liquid‐electrolyte junction devices. Of particular importance to the design of such devices is the control of interfacial charge transfer. In this paper, the factors that determine the yield of hole transfer at the dye/HTM interface and its correlation with solid‐state‐cell performance are identified. To this end, a series of novel triarylamine type oligomers, varying in molecular weight and mobility, are studied. Transient absorption spectroscopy is used to determine hole‐transfer yields and pore‐penetration characteristics. No correlation between hole mobility and cell performance is observed. However, it is found that the photocurrent is directly proportional to the hole‐transfer yield. This hole‐transfer yield depends on the extent of pore penetration in the dye‐sensitized film as well as on the thermodynamic driving force Δ G dye–HTM for interfacial charge transfer. Future design of alternative solid‐state HTMs should focus on the optimization of pore‐filling properties and the control of interfacial energetics rather than on increasing material hole mobilities.

The heterodimeric CGRP receptor requires co-expression of calcitonin receptor-like receptor (CRLR) and an accessory protein called receptor activity-modifying protein (RAMP) 1 (McLatchie, L. M., Fraser, N. J., Main, M. J., Wise, A., Brown, J., Thompson, N., Solari, R., Lee, M. G., and Foord, S. M. (1998) Nature 393, 333-339). Several non-peptide CGRP receptor antagonists have been shown to exhibit marked species selectivity, with >100-fold higher affinities for the human CGRP receptor than for receptors from other species (Doods, H., Hallermayer, G., Wu, D., Entzeroth, M., Rudolf, K., Engel, W., and Eberlein, W. (2000) Br. J. Pharmacol. 129, 420-423; Edvinsson, L., Sams, A., Jansen-Olesen, I., Tajti, J., Kane, S. A., Rutledge, R. Z., Koblan, K. S., Hill, R. G., and Longmore, J. (2001) Eur. J. Pharmacol. 415, 39-44). This observation provided an opportunity to map the determinants of receptor affinity exhibited by BIBN4096BS and the truncated analogs, Compounds 1 and 2. All three compounds exhibited higher affinity for the human receptor, human CRLR/human RAMP1, than for the rat receptor, rat CRLR/rat RAMP1. We have now demonstrated that this species selectivity was directed exclusively by RAMP1. By generating recombinant human/rat CRLR/RAMP1 receptors, we demonstrated that co-expression of human CRLR with rat RAMP1 produced rat receptor pharmacology, and vice versa. Moreover, with rat/human RAMP1 chimeras and site-directed mutants, we have identified a single amino acid at position 74 of RAMP1 that modulates the affinity of small molecule antagonists for CRLR/RAMP1. Replacement of lysine 74 in rat RAMP1 with tryptophan (the homologous amino acid in the human receptor) resulted in a > or =100-fold increase in antagonist affinities, similar to the K(i) values for the human receptor. These observations suggest that important determinants of small molecule antagonist affinity for the CGRP receptor reside within the extracellular region of RAMP1 and provide evidence that this receptor accessory protein may participate in antagonist binding.