Synthesis, thin-film morphology, and comparative study of bulk and bilayer heterojunction organic photovoltaic devices using soluble diketopyrrolopyrrole molecules

Diketopyrrolopyrrole (DPP)-based organic semiconductors EH-DPP-TFP and EH-DPP-TFPV with branched ethyl-hexyl solubilizing alkyl chains and end capped with trifluoromethyl phenyl groups were designed and synthesized via Suzuki coupling. These compounds show intense absorptions up to 700 nm, and thin film-forming characteristics that sensitively depend on the solvent and coating conditions. Both materials have been used as electron donors in bulk heterojunction and bilayer organic photovoltaic (OPV) devices with fullerenes as acceptors and their performance has been studied in detail. The best power conversion efficiency of 3.3% under AM1.5G illumination (100 mW cm -2) was achieved for bilayer solar cells when EH-DPP-TFPV was used with C 60, after a thermal annealing step to induce dye aggregation and interdiffusion of C 60 with the donor material. To date, this is one of the highest efficiencies reported for simple bilayer OPV devices.

Development of a dragline in-bucket bulk density monitor

This paper details the implementation and trialling of a prototype in-bucket bulk density monitor on a production dragline. Bulk density information can provide feedback to mine planning and scheduling to improve blasting and consequently facilitating optimal bucket sizing. The bulk density measurement builds upon outcomes presented in the AMTC2009 paper titled ‘Automatic In-Bucket Volume Estimation for Dragline Operations’ and utilises payload information from a commercial dragline monitor. While the previous paper explains the algorithms and theoretical basis for the system design and scaled model testing this paper will focus on the full scale implementation and the challenges involved.

Dynamics of nitrogen and suspended solids removal in experimental stormwater biofilters under intermittent wetting and drying

This research study comprehensively analyses the dynamics of nitrogen and suspended solids removal in stormwater biofilters. The study focuses on pollutant removal during an event with time, rather than the conventional event-mean analysis. Antecedent dry days (number of days in between rainfall) during which biofilters remain dry and the inflow concentration of pollutants were two other important variables analysed in this study. The research outcome highlights the significance of dry-phase processes and the process of stabilization on filter performance and sets a paradigm shift from the current approach towards an innovative way of performance analysis of biofilters.

Hydraulic conductivity increases in a sodic clay soil in response to gypsum applications impacts of bulk density and cation exchange

Amelioration of sodic soils is commonly achieved by applying gypsum, which increases soil hydraulic conductivity by altering soil chemistry. The magnitude of hydraulic conductivity increases expected in response to gypsum applications depends on soil properties including clay content, clay mineralogy, and bulk density. The soil analyzed in this study was a kaolinite rich sodic clay soil from an irrigated area of the Lower Burdekin coastal floodplain in tropical North Queensland, Australia. The impact of gypsum amelioration was investigated by continuously leaching soil columns with a saturated gypsum solution, until the hydraulic conductivity and leachate chemistry stabilized. Extended leaching enabled the full impacts of electrolyte effects and cation exchange to be determined. For the columns packed to 1.4 g/cm3, exchangeable sodium concentrations were reduced from 5.0 ± 0.5 mEq/100 g to 0.41 ± 0.06 mEq/100 g, exchangeable magnesium concentrations were reduced from 13.9 ± 0.3 mEq/100 g to 4.3 ± 2.12 mEq/100 g, and hydraulic conductivity increased to 0.15 ± 0.04 cm/d. For the columns packed to 1.3 g/cm3, exchangeable sodium concentrations were reduced from 5.0 ± 0.5 mEq/100 g to 0.51 ± 0.03 mEq/100 g, exchangeable magnesium concentrations were reduced from 13.9 ± 0.3 mEq/100 g to 0.55 ± 0.36 mEq/100 g, and hydraulic conductivity increased to 0.96 ± 0.53 cm/d. The results of this study highlight that both sodium and magnesium need to be taken into account when determining the suitability of water quality for irrigation of sodic soils and that soil bulk density plays a major role in controlling the extent of reclamation that can be achieved using gypsum applications.

An Electron-Accepting Chromophore Based on Fluorene and Naphthalenediimide Building Blocks for Solution-Processable Bulk Heterojunction Devices

We have designed, synthesized and utilized a new non-fullerene electron acceptor, 9,9′-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(2,7-dioctyl-4-(octylamino)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone) (B2), for use in solution-processable bulk-heterojunction devices. B2 is based on a central fluorene moiety, which was capped at both ends with an electron-accepting naphthalenediimide functionality. B2 exhibited excellent solubility (>30 mg mL−1 in chloroform), high thermal and photochemical stability, and appropriate energy levels for use with the classical polymer donor regioregular poly(3-hexylthiophene). A power conversion efficiency of 1.16 % was achieved for primitive bulk-heterojunction devices with a high fill factor of approximately 54 %.

Conjoint use of Dibenzosilole and Indan-1,3-dione Functionalities to Prepare an Efficient Non-Fullerene Acceptor for Solution-Processable Bulk-Heterojunction Solar Cells

A solution-processable, non-fullerene electron acceptor, 2,2′-(((5,5-dioctyl-5 H-dibenzo[b,d]silole-3,7-diyl)bis(thiophene-5,2-diyl))bis(methanylylidene))bis(1 H-indene-1,3(2 H)-dione) (called N5) comprised of dibenzosilole and 1,3-indanedione building blocks was designed, synthesized, and fully characterized. N5 is highly soluble in various organic solvents, has high thermal stability, and has energy levels matching those of archetypal donor poly(3-hexylthiophene). Solution-processable, bulk-heterojunction solar cells afforded promising power conversion efficiency of 2.76 % when N5 was used as a non-fullerene electron acceptor along with the conventional donor polymer poly(3-hexylthiophene). As per our knowledge, the material reported herein is the first example in the literature where synchronous use of such building blocks is demonstrated in the design an efficient, non-fullerene acceptor.

Group 14 element-based non-centrosymmetric quantum spin hall insulators with large bulk gap

To date, a number of two-dimensional (2D) topological insulators (TIs) have been realized in Group 14 elemental honeycomb lattices, but all are inversionsymmetric. Here, based on first-principles calculations, we predict a new family of 2D inversion-asymmetric TIs with sizeable bulk gaps from 105 meV to 284 meV, in X2–GeSn (X = H, F, Cl, Br, I) monolayers, making them in principle suitable for room-temperature applications. The nontrivial topological characteristics of inverted band orders are identified in pristine X2–GeSn with X = (F, Cl, Br, I), whereas H2–GeSn undergoes a nontrivial band inversion at 8% lattice expansion. Topologically protected edge states are identified in X2–GeSn with X = (F, Cl, Br, I), as well as in strained H2–GeSn. More importantly, the edges of these systems, which exhibit single-Dirac-cone characteristics located exactly in the middle of their bulk band gaps, are ideal for dissipationless transport. Thus, Group 14 elemental honeycomb lattices provide a fascinating playground for the manipulation of quantum states.

Wave propagation in elastic solids undergoing damage and growth process

Modeling and analysis of wave propagation in elastic solids undergoing damage and growth process are reported in this paper. Two types of diagnostic problems, (1) the propagation of waves in the presence of a slow growth process and (2) the propagation of waves in the presence of a fast growth process, are considered. The proposed model employs a slow and a fast time scale and a homogenization technique in the wavelength scale. A detailed analysis of wave dispersion is carried out. A spectral analysis reveals certain low-frequency bands, where the interaction between the wave and the growth process produces acoustic metamaterial-like behavior. Various practical issues in designing an efficient method of acousto-ultrasonic wave based diagnostics of the growth process are discussed. Diagnostics of isotropic damage in a ductile or quasi-brittle solid by using a micro-second pulsating signal is considered for computer simulations, which is to illustrate the practical application of the proposed modeling and analysis. The simulated results explain how an estimate of signal spreading can be effectively employed to detect the presence of a steady-state damage or the saturation of a process.

Time-temperature histories of spherical food products during bulk forced-air precooling

A general mathematical model for forced air precooling of spherical food products in bulk is developed. The food products are arranged inline to form a rectangular parallelepiped. Chilled air is blown along the height of the package. The governing equations for the transient two-dimensional conduction with internal heat generation in the product, simultaneous heat and mass transfer at the product-air interface and one-dimensional transient energy and species conservation equations for the moist air are solved numerically using finite difference methods. Results are presented in the form of time-temperature histories. Experiments are conducted with model foods in a laboratory scale air precooling tunnel. The agreement between the theoretical and experimental results is found to be good. In general, a single product analysis fails to predict the precooling characteristics of bulk loads of food products. In the range of values investigated, the respiration heat is found to have a negligible effect.

Micropillar compression studies on a bulk metallic glass in different structural states

Uniaxial compression experiments on 0.3, 1 and 3 mu m diameter micropillars of a Zr-based bulk metallic glass in as-cast, shot-peened and structurally relaxed conditions were conducted. Shear band formation and stable propagation is observed to be the plastic deformation mode in all cases, with no detectable difference in yield strength according to either size or condition. The limitations of uniaxial compression tests in assessing the influence of various material conditions on plasticity, when it is inhomogeneous in nature, are illustrated.

Towards rational synthesis of inorganic solids

There have been major advances in the past couple of years in the rational synthesis of inorganic solids: synthesis of mercury-based superconducting cuprates showing transition temperatures up to 150 K; ZrP2-xVxO7 solid solutions showing zero or negative thermal expansion; copper oxides possessing ladder structures such as La1-xSrxCuO2.5; synthesis of mesoporous oxide materials having adjustable pore size in the range 15-100 Angstrom; and synthesis of a molecular ferromagnet showing a critical temperature of 18.6 K. Despite great advances in probing the structures of solids and measurement of their physical properties, the design and synthesis of inorganic solids possessing desired structures and properties remain a challenge today. With the availability of a variety of mild chemistry-based approaches, kinetic control of synthetic pathways is becoming increasingly possible, which, it is hoped, will eventually make rational design of inorganic solids a reality.

Unusual effect of tellurium doping on the electrical-properties of bulk amorphous selenium

Abstract is not available.

Metal chelates in vinyl polymerization: Bulk polymerization of acrylonitrile initiated by Cu(II)-imine complexes

This article deals with the kinetics and mechanism of acrylonitrile (AN) polymerization initiated by Cu(II)-4-anilino 3-pentene 2-one[Cu(II)ANIPO], Cu(II)-4-p-toluedeno 3-pentene 2-one [Cu(II)TPO], and Cu(II)-4-p-nitroanilino 3-pentene 2-one [Cu(II)NAPO] in bulk at 60°C. The polymerization is free radical in nature. The exponent of initiator(I) is 0.5. The initiation step is a complex formation between the chelate and monomer and subsequent decomposition of the intermediate complex giving rise to free radical and Cu(I). This is substantiated by ultraviolet (UV) and electron spin resonance (ESR) studies. The activation energies and kinetic and chain transfer constants have also been evaluated.