Polyelectrolyte interlayers with a broad processing window for high efficiency inverted organic solar cells towards mass production

Neutral polyelectrolyte interfacial layers in organic solar cells are well-known for their ability to tailor the work function of electrodes, improve charge carrier extraction and maximize open circuit voltage. However, they also suffer from low charge carrier conductivity, and therefore the interlayer must be kept thin, which in turn requires very precise deposition. This prerequisite significantly reduces the robustness of the fabrication process and makes such structures difficult to up-scale for roll-to-roll mass production. Herein, we find that by washing the polyelectrolyte layer with N,N-dimethylformamide (DMF) after deposition, solar cell efficiency jumps to near optimum levels, no matter what the original thickness of the polyelectrolyte layer. Subsequent characterization of the DMF-washed ZnO/PEI interlayer reveals a changed surface structure, passivated surface trap states, and thus improved transport properties and lower recombination losses. We demonstrate the general applicability of the method to other state-of-the-art material systems, namely P3HT:ICBA, PTB7:PC71BM and PTB7-Th:PC71BM. We find that the more efficient the material system, the larger the improvement in efficiency after DMF washing. Thus, this method represents a general way to relax the fabrication criteria for high efficiency organic solar cells. We anticipate that this method could be of use in other classes of devices such as OTFTs and OLEDs

Rational design of biosafe crop resistance to a range of nematodes using RNA interference

Double stranded RNA (dsRNA) molecules targeting two genes have been identified that suppress economically important parasitic nematode species of banana. Proteasomal Alpha Subunit 4 (pas-4) and Actin-4 (act-4) were identified from a survey of sequence databases and cloned sequences for genes conserved across four pests of banana, Radopholus similis, Pratylenchus coffeae, Meloidogyne incognita and Helicotylenchus multicinctus. These four species were targeted with dsRNAs containing exact 21 nucleotide matches to the conserved regions. Potential off-target effects were limited by comparison to Caenorhabditis, Drosophila, rat, rice and Arabidopsis genomes. In vitro act-4 dsRNA treatment of R. similis suppressed target gene expression by 2.3 fold, nematode locomotion by 66 ± 4% and nematode multiplication on carrot discs by 49 ± 5%. The best transgenic carrot hairy root lines expressing act-4 or pas-4 dsRNA reduced transcript message abundance of target genes in R. similis by 7.9 fold and 4 fold and nematode multiplication by 94 ± 2% and 69 ± 3%, respectively. The same act-4 and pas-4 lines reduced P. coffeae target transcripts by 1.7 and 2 fold and multiplication by 50 ± 6% and 73 ± 8%. Multiplication of M. incognita on the pas-4 lines was reduced by 97 ± 1% and 99 ± 1% while target transcript abundance was suppressed 4.9 and 5.6 fold. There was no detectable RNAi effect on non-target nematodes exposed to dsRNAs targeting parasitic nematodes. This work defines a framework for development of a range of non-protein defences to provide broad resistance to pests and pathogens of crops

Coexistence of spin canting and metamagnetism in a one-dimensional Mn(II) compound bridged by alternating double end-to-end and double end-on azido ligands and the analog co(II) compound

Metals in Catalysis, Biomimetics & Inorganic Material

Combining plasmonic trap filling and optical backscattering for highly efficient third generation solar cells

© The Royal Society of Chemistry. Metal oxide contact layers such as ZnO and TiOx are commonly used in third generation solar cells as they can be solution processed and have a relatively high conductivity. It is well known that by ultraviolet (UV) light-soaking such devices, their overall device efficiency can be boosted. This improvement in efficiency is due to high energy UV light exciting hot carriers which then fill the trap states in the metal oxide film. Unfortunately, UV causes degradation of the active layer and thus must be filtered out if long lifetimes are to be achieved. In this work, we use plasmonically excited metal nano-structures embedded in a ZnO metal oxide layer to generate hot charge carriers from visible light alone, thus removing the need for UV light soaking. Using this approach, the solar cells also exhibit better charge transport/recombination properties as well as enhanced light trapping behavior. We demonstrate that the power conversion efficiency of a low-bandgap thieno[3,4-b]thiophene/benzodithiophene (PTB7) based solar cell can be increased from 7.91% to 9.36%

A FN-MdV pathway and its role in cerebellar multimodular control of sensorimotor behavior

The cerebellum is crucial for various associative sensorimotor behaviors. Delay eyeblink conditioning (DEC) depends on the simplex lobule-interposed nucleus (IN) pathway, yet it is unclear how other cerebellar modules cooperate during this task. Here, we demonstrate the contribution of the vermis-fastigial nucleus (FN) pathway in controlling DEC. We found that task-related modulations in vermal Purkinje cells and FN neurons predict conditioned responses (CRs). Coactivation of the FN and the IN allows for the generation of proper motor commands for CRs, but only FN output fine-tunes unconditione

Strategies for Improving the Photocatalytic Hydrogen Evolution Reaction of Carbon Nitride-Based Catalysts

Published online:. OnlinePublDue to the depletion of fossil fuels and their-related environmental issues, sustainable, clean, and renewable energy is urgently needed to replace fossil fuel as the primary energy resource. Hydrogen is considered as one of the cleanest energies. Among the approaches to hydrogen production, photocatalysis is the most sustainable and renewable solar energy technique. Considering the low cost of fabrication, earth abundance, appropriate bandgap, and high performance, carbon nitride has attracted extensive attention as the catalyst for photocatalytic hydrogen production in the last two decades. In this review, the carbon nitride-based photocatalytic hydrogen production system, including the catalytic mechanism and the strategies for improving the photocatalytic performance is discussed. According to the photocatalytic processes, the strengthened mechanism of carbon nitride-based catalysts is particularly described in terms of boosting the excitation of electrons and holes, suppressing carriers recombination, and enhancing the utilization efficiency of photon-excited electron-hole. Finally, the current trends related to the screening design of superior photocatalytic hydrogen production systems are outlined, and the development direction of carbon nitride for hydrogen production is clarified.Xueze Chu, C.I. Sathish, Jae-Hun Yang, Xinwei Guan, Xiangwei Zhang, Liang Qiao, Kazunari Domen, Shaobin Wang, Ajayan Vinu, and Jiabao Y

Invariant NKT cells limit activation of autoreactive CD1d-positive B cells

Faulty activation of autoreactive B cells is a hallmark of autoimmune diseases like systemic lupus erythematosus (SLE). An important feature restricting activation of autoreactive B cells is efficient removal of apoptotic material. Mounting evidence also connects a primary defect in invariant natural killer T (iNKT) cells to autoimmune disease development. However, exactly how this unconventional T cell subset is involved remains to be defined. Here, we identify a suppressive role for iNKT cells in a model where autoantibody production is triggered by an increased load of circulating apoptotic cells, resembling the situation in SLE patients. Absence or reduction of iNKT cells as well as absence of CD1d-expression on B cells, needed for direct iNKT–B cell interaction, leads to increased autoreactive B cell activation and symptoms of disease. The suppression mediated by the iNKT cells is observed before B cell entry into germinal centers and can be rescued by transferring iNKT cells to deficient mice. This links iNKT cells to handling of dying cells and identifies a novel peripheral tolerance checkpoint relevant for autoimmune disease. Thus, these observations connect two clinical observations in SLE patients previously considered to be unrelated and define a new target for immunotherapy

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let