Numerical Investigation of Graphene as a Back Surface Field Layer on the Performance of Cadmium Telluride Solar Cell

This paper numerically explores the possibility of ultrathin layering and high efficiency of graphene as a back surface field (BSF) based on a CdTe solar cell by Personal computer one-dimensional (PC1D) simulation. CdTe solar cells have been characterized and studied by varying the carrier lifetime, doping concentration, thickness, and bandgap of the graphene layer. With simulation results, the highest short-circuit current (I_sc = 2.09 A), power conversion efficiency (η = 15%), and quantum efficiency (QE~85%) were achieved at a carrier lifetime of 1 × 10³ μs and a doping concentration of 1 × 10¹⁷ cm⁻³ of graphene as a BSF layer-based CdTe solar cell. The thickness of the graphene BSF layer (1 μm) was proven the ultrathin, optimal, and obtainable for the fabrication of high-performance CdTe solar cells, confirming the suitability of graphene material as a BSF. This simulation confirmed that a CdTe solar cell with the proposed graphene as the BSF layer might be highly efficient with optimized parameters for fabrication.     

Phenothiazine–BODIPY–Fullerene Triads as Photosynthetic Reaction Center Models: Substitution and Solvent Polarity Effects on Photoinduced Charge Separation and Recombination

Novel photosynthetic reaction center model compounds of the type donor₂–donor₁–acceptor, composed of phenothiazine, BF₂‐chelated dipyrromethene (BODIPY), and fullerene, respectively, have been newly synthesized using multistep synthetic methods. X‐ray structures of three of the phenothiazine‐BODIPY intermediate compounds have been solved to visualize the substitution effect caused by the phenothiazine on the BODIPY macrocycle. Optical absorption and emission, computational, and differential pulse voltammetry studies were systematically performed to establish the molecular integrity of the triads. The N‐substituted phenothiazine was found to be easier to oxidize by 60 mV compared to the C‐substituted analogue. The geometry and electronic structures were obtained by B3LYP/6‐31G(dp) calculations (for H, B, N, and O) and B3LYP/6‐31G(df) calculations (for S) in vacuum, followed by a single‐point calculation in benzonitrile utilizing the polarizable continuum model (PCM). The HOMO?1, HOMO, and LUMO were, respectively, on the BODIPY, phenothiazine and fullerene entities, which agreed well with the site of electron transfer determined from electrochemical studies. The energy‐level diagram deduced from these data helped in elucidating the mechanistic details of the photochemical events. Excitation of BODIPY resulted in ultrafast electron transfer to produce PTZ–BODIPY^.+–C₆₀^.?; subsequent hole shift resulted in PTZ^.+–BODIPY–C₆₀^.? charge‐separated species. The return of the charge‐separated species was found to be solvent dependent. In nonpolar solvents the PTZ^.+–BODIPY–C₆₀^.? species populated the ³C₆₀* prior to returning to the ground state, while in polar solvent no such process was observed due to relative positioning of the energy levels. The ¹BODIPY* generated radical ion‐pair in these triads persisted for few nanoseconds due to electron transfer/hole‐shift mechanism.     

Nickel‐Catalyzed α‐Carbonylalkylarylation of Vinylarenes: Expedient Access to γ,γ‐Diarylcarbonyl and Aryltetralone Derivatives

We report a Ni‐catalyzed regioselective α‐carbonylalkylarylation of vinylarenes with α‐halocarbonyl compounds and arylzinc reagents. The reaction works with primary, secondary, and tertiary α‐halocarbonyl molecules, and electronically varied arylzinc reagents. The reaction generates γ,γ‐diarylcarbonyl derivatives with α‐secondary, tertiary, and quaternary carbon centers. The products can be readily converted to aryltetralones, including a precursor to Zoloft, an antidepressant drug.     

Backside laser etching of fused silica using liquid gallium

Laser-induced backside wet etching (LIBWE) that is regularly performed with hydrocarbon solutions is demonstrated with the liquid metal gallium as a new class of absorbers for the first time. Well-contoured square etch pits in fused silica with smooth bottoms and well-defined edges were achieved already with the first pulse from a 248 nm excimer laser. The etching is characterized by a threshold fluence of 1.3 J/cm² and a straight proportional etch rate growth with the fluence up to 8.2 J/cm². In addition, the etch depth increases linearly for onward pulsed laser irradiation and gives evidence for an only marginal incubation effect. The high fluences necessary for etching originate from the high reflection losses as well as the high thermal conductivity of the metallic absorber. The suggested etch mechanism comprises the heating of the fused silica up to or beyond the fused silica melting point by the laser heated gallium and the removing of the softened or molten fraction of the material by mechanical forces from shock waves, bubbles, high pressures, or stress fields. PACS 81.65.C; 81.05.J; 79.20.D; 61.80.B; 42.55.L     

Synthese und spektroskopische Charakterisierung einiger Pentacarbonylwolfram(0)-Komplexe mit verschiedenen 1H-Phosphiren-Liganden,Kristallstrukturen von,und

Synthesis and Spectroscopic Characterization of some Pentacarbonyltungsten(0) Complexes with Various 1H-Phosphirene Ligands: Crystal Structures of , and The tungsten(0) complex 1 reacts upon heating with acetylene derivatives 2a–f in toluene to form benzonitrile and the complexes 4a–f ( 4a : R¹ ? Ph, R² ? H; 4b : R¹ ? Ph, R² ? CH₃; 4c : R¹ ? OEt, R² ? H; 4d : R¹ ? Ph, R² ? CO₂Et; 4e : R¹, R² ? CO₂Me; 4f : R¹, R² ? SiMe₃), which have been isolated by chromatography. Spectroscopic and mass spectrometric data are discussed. The crystal structures of the compounds 4a, b and d were determined by X-ray single crystal structure analysis ( 4a : space group P2₁/n, Z = 4, a = 937,5(2) pm, b = 2202,4(6) pm, c = 1266,3(4) pm, β = 108,94(4)°; 4b : space group P2₁/c, Z = 4, a = 1293,9(2) pm, b = 923,5(1) pm, c = 2223,4(3) pm, β = 92,385(6)°; 4d : space group P2₁/c, Z = 4, a = 955,2(2) pm, b = 3190,9(4) pm, c = 930,7(2) pm, β = 99,64(1)°).     

Erste Reaktionen an der P=C- und an der P–P-Bindung des neuen P-Phosphanylphosphaalkens 1-Bis(trimethylsilyl)methyliden-2,2-diisopropyldiphosphan

The New P -Phosphanylphosphaalkene 1-Bis(trimethylsilyl)methylidene-2,2-diisopropyldiphosphane: First Reactions at its P=C and P–P Bonds (Me₃Si)₂C=PCl ( 1 ) reacts with the trichlorosilylphosphanes RR′PSiCl₃ (R and R′ = t-Bu or i-Pr) providing the new P-dialkylphosphanylphosphaalkenes (Me₃Si)₂C=P–P-i-Pr₂ ( 2 ) and (Me₃Si)₂C=P–P(t-Bu)(i-Pr) ( 3 ) as well as the known (Me₃Si)₂C=P–P-t-Bu₂ ( 4 ). The P=C double bond of 2 can be protected reversibly by a [2 + 4]-cycloaddition with cyclopentadiene resulting in the formation of a P-phosphanyl-phosphanorbornene derivative 5 . The [2 + 4]-cycloaddition of 2 with 2,3-dimethylbutadiene provides the cyclic diphosphane 6 . Reactions of 2 with sulfur and selenium were followed by ³¹P and ⁷⁷Se nmr: Chalcogen insertion into the P–P bond leads to the products (Me₃Si)₂C=P–X–P-i-Pr₂ 9 a (X = S) and  9 b (X = Se). Subsequent σ³λ³ → σ⁴λ⁵ oxidation steps of 9 a with S and of 9 b with Se lead to compounds (Me₃Si)₂C=P–X–P(=X)-i-Pr₂ 10 a (X = S) and 10 b (X = Se), which contain phosphinic acid functions with the phosphaalkene moieties attached to S or Se. 10 a and 10 b were not isolated in a pure state. However, trapping 10 b from an enriched solution by [2 + 4]-cycloaddition with cyclopentadiene allowed the isolation of the P-diseleno-phosphinato-phosphanorbornene 12 . The constitution of new compounds 2 , 3 , 5 , 6 and 12 was confirmed by elemental analyses, nmr and mass spectra. The structures of cycloadducts 5 and 6 were determined by X-ray diffraction analysis.     

Brain-derived neurotrophic factor modulation of Kv1.3 channel is disregulated by adaptor proteins Grb10 and nShc

Background  

Neurotrophins are important regulators of growth and regeneration, and acutely, they can modulate the activity of voltage-gated ion channels. Previously we have shown that acute brain-derived neurotrophic factor (BDNF) activation of neurotrophin receptor tyrosine kinase B (TrkB) suppresses the Shaker voltage-gated potassium channel (Kv1.3) via phosphorylation of multiple tyrosine residues in the N and C terminal aspects of the channel protein. It is not known how adaptor proteins, which lack catalytic activity, but interact with members of the neurotrophic signaling pathway, might scaffold with ion channels or modulate channel activity.     

Magnetism and candidate muon-probe sites in RBa2Cu3O y

Key results of zero-field (ZF) and transverse-field (TF) muon-spin-relaxation (μSR) experiments on superconducting and insulating RBa₂Cu₃O _y (R123 _y , with R=Eu, Gd, Pr and Pr/Y:y=6, 7) are examined. The chemical behavior of the positive muon probe is addressed, and muon-oxygen bonding is shown to occur in all these cuprates. To explain magnetic fields at muon-probe sites in Pr _x Y_1−x Ba₂Cu₃O _y (0<=x<0.5,y=7 andx=0,y=6) samples, improvements on the reported magnetic structures from neutron diffraction are necessary. Cu magnetism in Pr123y (y=6,7) is observed belowT _N1, which is near RT. The magnetism seen belowT _N2 can be interpreted assuming an additional ordering in the Cutt-O chain layers. Alternatively, Pr ordering is also considered as the cause of the second phase transition. Considering the specific muon-probe location, a more detailed interpretation can be provided for the μSR parameters, measured in the normal and mixed states of these unconventional superconductors.