A review of graphene derivative enhancers for perovskite solar cells

Due to the finite nature, health and environmental hazards currently associated with the use of fossil energy resources, there is a global drive to hasten development and deployment of renewable energy technologies. One such area encompasses perovskite solar cells (PSCs) that have shown photoconversion efficiencies (PCE) comparable to silicon-based photovoltaics, but their commercialisation has been set back by short-term stability and toxicity issues, among others. A tremendous potential to overcome these drawbacks is presented by the emerging applications of graphene derivative-based materials in PSCs as substitutes or components, composites with other functional materials, and enhancers of charge transport, blocking action, exciton dissociation, substrate coverage sensitisation and stabilisation. This review aims to illustrate how these highly capable carbon-based materials can advance PSCs by critically outlining and discussing their current applications and strategically identifying prospective research avenues. The reviewed works show that graphene derivatives have great potential in boosting the performance and stability of PSCs through morphological modifications and compositional engineering. This can drive the sustainability and commercial viability aspects of PSCs

P-wave meson properties with Wilson quarks

We describe two calculations involving P-wave mesons made of Wilson quarks: the strong coupling constant $\alpha_s$ in the presence of two flavors of light dynamical fermions and the mass and decay constant of the $a_1$ meson.Comment: Poster presented at Lattice '94, September 27--October 1, 1994, Bielefeld, Germany (no changes to manuscript, but correction of Authors list above

Effects of Cold-formed Steel Framed Gypsum Partition Walls on the Seismic Response of a Medical Facility

The first experimental phase of the NEES Nonstructural Grand Challenge Project: “Simulation of the Seismic Performance of Nonstructural Systems” investigated the in-plane hysteretic behaviors of thirty-six full-scale cold-formed steel framed gypsum partition walls. Results of quasi-static reverse cyclic and dynamic testing on sixteen wall configurations including walls with commercial and institutional construction details and innovative connection techniques are first briefly reviewed. Thereafter, six tri-linear hysteretic models of partition walls with pinching behavior and strength and stiffness degradation are developed based on the experimental data for use in a finite element analysis platform. The partition wall models, represented by shear spring elements at each floor level, are incorporated into a numerical model of a four story steel moment frame medical facility. Although nonstructural components are required to carry self-imposed loads and minimal external loads and are not required to be considered in the structural analysis and design of buildings, the addition of the partition walls are shown to increase the stiffness and strength of the building, reducing the natural period by more than 11%. Furthermore, partition walls are shown to introduce over 42% more damping into the building due to the continual energy dissipation through their pinched hysteretic behaviors. The effect of the nonstructural partition walls on the inter-story displacements and absolute accelerations is also examined

γ‐Valerolactone: A Nontoxic Green Solvent for Highly Stable Printed Mesoporous Perovskite Solar Cells

Mesoscopic carbon-based lead halide perovskite solar cells (CPSCs) represent a promising architecture for commercialization in the field of perovskite photovoltaics as they are stable, potentially low cost, and use easily scaled production methods. However, the use of toxic and psychoactive solvents such as dimethylformamide (DMF) and γ-butyrolactone (GBL) currently limits their commercial viability: DMF introduces a significant health risk and GBL is subject to legal restrictions in many countries. The development of safe and effective solvent systems is therefore an essential step toward commercial viability. Herein, γ-valerolactone (GVL) is presented as a nontoxic, biodegradable, green alternative to GBL for CPSC fabrication. Cells fabricated with a precursor concentration of 1.1 m and annealed at 45 °C exhibit comparable performance to standard GBL devices, achieving a champion power conversion efficiency (PCE) of 12.91% in a device of 1 cm2 active area. Herein, it is proven that GVL is a viable alternative to GBL for CPSCs and enables research in countries where GBL is legally restricted and makes large-scale CPSC manufacture more sustainable

Next-to-Leading Order QCD Corrections and Massive Quarks in e+e−→3e^+e^-\to 3 Jets

We present in detail a calculation of the next-to-leading order QCD corrections to the process $e^+e^-\to 3$ jets with massive quarks. To isolate the soft and collinear divergencies of the four parton matrix elements, we modify the phase space slicing method to account for masses. Our computation allows for the prediction of oriented three jet events involving heavy quarks, both on and off the Z resonance, and of any event shape variable which is dominated by three jet configurations. We show next-to-leading order results for the three jet fraction, the differential two jet rate, and for the thrust distribution at various c.m. energies.Comment: 51 pages, LaTeX, 16 postscript figure

A Precise Determination of αs\alpha_s from Lattice QCD

We present a new determination of the QCD strong coupling constant based on precise lattice calculations of the $\Upsilon$ spectrum. The largest systematic uncertainty in previous such determinations resulted from the absence of vacuum polarization from light quarks. We substantially reduce this error by including two flavors of dynamical light quarks and extrapolating to three. We find \alphathree_\V(8.2~\GeV) = 0.196(3) for three light flavors, corresponding to \alphafive_\msbar(M_Z) = 0.115(2). This is significantly more accurate than previous determinations using this or any other technique.Comment: 11 pages (LaTeX), OHSTPY-HEP-T-94-013, FSU-SCRI-94-79 (includes minor corrections in tables, additional references