Search

We report the band gap tuning and facilitated charge transport at perylenediimide (PDI)/GaN interface in organic–inorganic hybrid nanostructure system over flexible titanium (Ti) foil. Energy levels of the materials perfectly align and facilitate high efficiency charge transfer from electron rich n-GaN to electron deficient PDI molecules. Proper interface formation resulted in band gap tuning as well as facilitated electron transport as evident in I–V characteristics. Growth of PDI/GaN hybrid system with band gap tuning from ultra-violet to visible region and excellent electrical properties open up new paradigm for fabrication of efficient optoelectronics devices on flexible substrates. [ABSTRACT FROM AUTHOR]

Carbon molecular sieve (CMS) membranes offer key advantages over current polymer membranes for challenging gas separations. Excellent plasticization resistance and high selectivity with low permeance loss at subambient temperatures also make CMS attractive for potential hybrid post combustion CO 2 capture technology. Here we describe highly permeable ultra-thin skin CMS (ULT-CMS) membranes with CO 2 permeance >3000 GPU at 35 °C and >2500 GPU at −20 °C with 2-3x increase in CO 2 /N 2 selectivity at subambient temperaures. Dual layer polymer precursors fibers comprising Matrimid® with polyvinylpyrrolidone (PVP), a pore forming polymer, are used to create a substructure support, while 6FDA/BPDA-DAM polymer comprises the thin sheath layer. Two different skin thickness and outer diameter polymer precursor membranes were prepared by varying the spinning parameters to study the effect on CMS performance. Polymer precursor membranes were pretreated with 10% VTMS (vinyltriethoxysilane) to avoid substructure collapse and 0.1% DETDA (3,5-diethyltoluenediamine)/TMC (1,3,5 Bezenetricarbonyltrichloride) hybridization treatment is used to heal nanoscopic defects before pyrolysis. The precursor fibers, pyrolyzed at 550 °C, create highly permeable CMS membranes for CO 2 /N 2 separation with high selectivity at ambient and subambient temperaures as noted above. • Preparation of highly permeable ultrathin skin CMS membranes for CO2/N2 separation at ambient and subambient temperatur • 2. CO2 permeance of 20x and 25x higher than current CMS membranes at ambient and subambient temperatures, respectively • 3. Robust with ~15% loss in permeance at subambient temperatures and 15-25% loss on cycling back to ambient temperatures. • These membranes show highly attractive performance for cryogenic-membrane hybrid carbon capture technology. [ABSTRACT FROM AUTHOR]

We have covalently grafted fullerene molecules to graphene oxide using hydrolyzed PCBM as fullerene precursor via very mild process without the use of metal catalysts and comprehensively studied the charge transfer interactions in ground and excited state. For the evidence of covalent grafting of fullerene on graphene oxide sheets different spectroscopic studies have been performed like, FTIR, Raman spectroscopy, UV–vis absorption, cyclic voltammetry, XRD and XPS. Amount of loading of fullerene on graphene oxide is calculated by thermogravimetric analysis and morphological study was performed by AFM and TEM. Covalently attached fullerene molecules act as excellent electron acceptor for ultrafast electron transfer from graphene oxide sheets and established by photoluminescence and ultrafast pump-probe transient absorption (TA) spectroscopy. From the TA measurements, we reveal ultrafast charge separation and long lived charge separated species formation in fullerene functionalized graphene oxide. [ABSTRACT FROM AUTHOR]

In this paper, we report the magnetic, heat capacity and magneto-caloric effect (MCE) of amorphous Gd7Ru3 compound. Both, temperature dependent magnetization and heat capacity data reveals that two transitions at 58 K and 34 K. MCE has been calculated in terms of isothermal entropy change (ΔSM) and adiabatic temperature change (ΔTad) using the heat capacity data in different fields. The maximum values of ΔSM and ΔTad are 21 Jmol-1K-1 and 5 K respectively, for field change of 50 kOe whereas relative cooling power (RCP) is ~735 J/kg for the same field change. [ABSTRACT FROM AUTHOR]

Organic solar cell research has attracted scientific and commercial interest in the last decade due to a rapid increase in power conversion efficiencies (PCEs). Today, PCEs in the range of 8 - 1 0% have been obtained using conjugated polymers as electron-donor materials in combination with fullerene/other acceptors. However, to enable commercial applications, the efficiencies and lifetimes of organic solar cells still need to be improved significantly. In recent years, due to the potential advantages of Se-containing conjugated materials, namely, lower band gaps, rigidity, and strong Se-Se integration, have attracted surprising attention for use in organic solar cells. In this review, we focus on the synthesis and applications of Se-containing conjugated polymers for organic solar cells and throughout compare them with S- and O-containing analogues where applicable. The relationships between the chemical structures and properties, such as absorptions, energy levels, mobilities, and photovoltaic behavior, are also discussed. [ABSTRACT FROM AUTHOR]

During development in maize, chloroplast and mitochondrial DNA damage increases, copy number of unimpeded DNA molecules decreases, and in vitro DNA repair increases, with light causing the greatest change.The amount and structural integrity of organellar DNAs change during plant development, although the mechanisms of change are poorly understood. Using PCR-based methods, we quantified DNA damage, molecular integrity, and genome copy number for plastid and mitochondrial DNAs of maize seedlings. A DNA repair assay was also used to assess DNA impediments. During development, DNA damage increased and molecules with impediments that prevented amplification by Taq DNA polymerase increased, with light causing the greatest change. DNA copy number values depended on the assay method, with standard real-time quantitative PCR (qPCR) values exceeding those determined by long-PCR by 100- to 1000-fold. As the organelles develop, their DNAs may be damaged in oxidative environments created by photo-oxidative reactions and photosynthetic/respiratory electron transfer. Some molecules may be repaired, while molecules with unrepaired damage may be degraded to non-functional fragments measured by standard qPCR but not by long-PCR. [ABSTRACT FROM AUTHOR]

Graphene is a wonder material possessing unique properties; however, graphene prepared by exfoliation of graphite has property to restack because of van der Waals interactions to form graphite. This restacking can be prevented by insertion of large molecules like fullerene, which not only exfoliates graphite layer but also prevents restacking of prepared graphene sheets. The present article also describes a mild method of graphite oxide synthesis (GO) for lower degree of oxidation resulting in less defected (ruptured carbon framework) graphene sheets. Exfoliation is performed by intercalation of large fullerene molecules by aqueous reaction of fullerene hydroxide (fullerenol) with the epoxy functionalities on graphite oxide to prepare fullerene intercalated graphite (G-Fol). Fullerene functionalization of GO to form G-Fol has been established by FTIR spectroscopy, UV-Vis spectroscopy, TGA and number of layers has been ascertained by Raman spectroscopy, XRD and HRTEM. Stable exfoliation of G-Fol has been confirmed by change in absorbance with time. Photoluminescence property of the material is also evaluated by fluorescence emission and excitation measurement at different excitation and emission wavelengths, respectively. The present article explains a new method of exfoliation of graphite to form stable functionalized graphene layers with fewer defects for future applications as buffer layer in electronic devices. [ABSTRACT FROM AUTHOR]

Organic solar cell research has attracted scientific and commercial interest in the last decade due to a rapid increase in power conversion efficiencies (PCEs). Today, PCEs in the range of 8-10?% have been obtained using conjugated polymers as electron-donor materials in combination with fullerene/other acceptors. However, to enable commercial applications, the efficiencies and lifetimes of organic solar cells still need to be improved significantly. In recent years, due to the potential advantages of Se-containing conjugated materials, namely, lower band gaps, rigidity, and strong Se···Se integration, have attracted surprising attention for use in organic solar cells. In this review, we focus on the synthesis and applications of Se-containing conjugated polymers for organic solar cells and throughout compare them with S- and O-containing analogues where applicable. The relationships between the chemical structures and properties, such as absorptions, energy levels, mobilities, and photovoltaic behavior, are also discussed. [ABSTRACT FROM AUTHOR]

A novel fabrication method for optical thin film filters based on the self-organization of alternating layers of colloidal gold and silica nanoparticles (NP) is reported. The filter is designed to work in the deep-UV to visible spectral range. The spectral absorption peaks are tuned by three parameters: the organic capping ligand of the gold NPs (citrate, chitosan, poly (diallyl-dimethylammonium)-chloride or PDDA); the capping environment (bare, chitosan, or PDDA) of the silica NPs and the thickness of the film. Precise control of the transmission color (less than 1% color distance per layer), is achieved by changing the film thickness. Exploitation of the self-assembly process should lead to the facile production of highly reliable large area thin film optical filters at considerably lower costs. [ABSTRACT FROM AUTHOR]

DNA sequences similar to those in the organellar genomes are also found in the nucleus. These non-coding sequences may be co-amplified by PCR with the authentic organellar DNA sequences, leading to erroneous conclusions. To avoid this problem, we describe an experimental procedure to prevent amplification of this 'promiscuous' DNA when total tissue DNA is used with PCR. First, primers are designed for organelle-specific sequences using a bioinformatics method. These primers are then tested using methylation-sensitive PCR. The method is demonstrated for both end-point and real-time PCR with Zea mays, where most of the DNA sequences in the organellar genomes are also present in the nucleus. We use this procedure to quantify those nuclear DNA sequences that are near-perfect replicas of organellar DNA. This method should be useful for applications including phylogenetic analysis, organellar DNA quantification and clinical testing. [ABSTRACT FROM AUTHOR]

Perennial woodland herbs in the genus Thalictrum exhibit high diversity of floral morphology, including four breeding and two pollination systems. Their phylogenetic position, in the early-diverging eudicots, makes them especially suitable for exploring the evolution of floral traits and the fate of gene paralogs that may have shaped the radiation of the eudicots. A current limitation in evolution of plant development studies is the lack of genetic tools for conducting functional assays in key taxa spanning the angiosperm phylogeny. We first show that virus-induced gene silencing (VIGS) of a PHYTOENE DESATURASE ortholog (TdPDS) can be achieved in Thalictrum dioicum with an efficiency of 42% and a survival rate of 97%, using tobacco rattle virus (TRV) vectors. The photobleached leaf phenotype of silenced plants significantly correlates with the down-regulation of endogenous TdPDS (P<0.05), as compared to controls. Floral silencing of PDS was achieved in the faster flowering spring ephemeral T. thalictroides. In its close relative, T. clavatum, silencing of the floral MADS box gene AGAMOUS (AG) resulted in strong homeotic conversions of floral organs. In conclusion, we set forth our optimized protocol for VIGS by vacuum-infiltration of Thalictrum seedlings or dormant tubers as a reference for the research community. The three species reported here span the range of floral morphologies and pollination syndromes present in Thalictrum. The evidence presented on floral silencing of orthologs of the marker gene PDS and the floral homeotic gene AG will enable a comparative approach to the study of the evolution of flower development in this group. [ABSTRACT FROM AUTHOR]

Here we report Sm2Al and Sm1.988Gd0.012Al compounds, with orthorhombic crystal structure (space group: Pnma), showing negative magnetization in temperature dependence magnetization data. Both compounds magnetically order at ~150 and 200K respectively and below this temperature, magnetization data shows a compensation temperature (Tcomp) which shifts with field. Hysteresis loops obtained below Tcomp signify that both Sm2Al and Sm1.988Gd0.012Al possess exchange anisotropy. Both, exchange anisotropy field and coercive field are found to be quite large and comparable to those of the classical spin-orbit compensated ferromagnet (Sm,Gd)Al2. [ABSTRACT FROM AUTHOR]

Investigates HIV1-infected pregnant tribal women from India to assess the rate and mode of transmission of perinatal infection and the natural history of maternally derived HIV infection in infancy and early childhood. Maternal status; Infant status; Infant deaths; Transmission rates.

• A comparative study has been performed for the device properties of two quaternary salts of PDI derivatives (PDI-Q) having aliphatic / aromatic substituents at imide position. • PDI-Q derivatives show suitable properties to be used as ETL like high transmittance in visible region, suitable HOMO-LUMO energy levels and good electron mobility. • Device with PDI-EDAQ with aliphatic substitution shows better device performance compared to PDI-PyQ with aromatic substituent due to better electron transport in the former improving the fill factor. • Theoretical simulation has also been performed to understand the difference in device properties of the two materials. This work describes the study of solution processable perylene diimide (PDI) derivatives bearing aliphatic (PDI-EDAQ) and aromatic (PDI-PyQ) substituents at imide position as electron transport layer (ETL) material for organic solar cells. The PDI derivatives are easy to synthesize and most importantly soluble in methanol for processing feasibility. The materials have been characterized for their opto-electronic and electrochemical properties. The electron mobility was calculated by fabricating electron only devices and finally were tested PDI derivatives in inverted organic solar cell devices as ETL material using PTB7:PC 71 BM as active layer. Average power conversion efficiency was found to be 4.2% and 2.2% for PDI-EDAQ and PDI-PyQ based devices respectively. The champion device for PDI-EDA showed efficiency ~4.5%. The device properties have been compared with standard ZnO ETL devices and by theoretical simulation an explanation has been provided for observed behaviour. [ABSTRACT FROM AUTHOR]

The broken time reversal symmetry states may result in the opening of a band gap in TlBiSe2 leading to several interesting phenomena which are potentially relevant for spintronic applications. In this work, the quantum interference and magnetic proximity effects have been studied in Ni80Fe20/p-TlBiSe2/p-Si (Magnetic/TI) heterostructure using physical vapor deposition technique. Raman analysis shows the symmetry breaking with the appearance of A21u mode. The electrical characteristics are investigated under dark and illumination conditions in the absence as well as in the presence of a magnetic field. The outcomes of the examined device reveal excellent photo response in both forward and reverse bias regions. Interestingly, under a magnetic field, the device shows a reduction in electrical conductivity at ambient conditions due to the crossover of weak localization and separation of weak antilocalization, which are experimentally confirmed by magnetoresistance measurement. Further, the photo response has also been assessed by the transient absorption spectroscopy through analysis of charge transfer and carrier relaxation mechanisms. Our results can be beneficial for quantum computation and further study of topological insulator/ferromagnet heterostructure and topological material based spintronic devices due to high spin orbit coupling along with dissipationless conduction channels at the surface states. [ABSTRACT FROM AUTHOR]

Abstract Flue gas CO 2 capture has received significant attention in recent years to mitigate the environmental impact of greenhouse gases. In spite of excellent performance by polymer membranes, there is still a need for more robust membranes to exceed the polymer upper bound at subambient temperatures, and carbon molecular sieve (CMS) membranes could offer a potential solution. In the present study, as a proof of concept, CMS hollow fiber membranes derived from defect-free 6FDA/BPDA-DAM polymer precursors at a pyrolysis temperature of 550 °C were investigated for CO 2 /N 2 separation. Both ambient (35 °C) and subambient (−20 °C) temperature performance for these CMS membranes have been studied using a combination of pressure decay sorption and permeation techniques. Permeation results using CO 2 /N 2 (20:80) mixed gas CMS showed CO 2 /N 2 selectivity of ~109 and CO 2 permeance of ~ 107 GPU at −20 °C. Most interestingly, a decrease of only ~ 33% in CO 2 permeance with a large increase in CO 2 /N 2 selectivity (~ 4.5 times) was observed for CMS membranes on decreasing temperature from 35 °C to −20 °C. Gas sorption measurements indicated that the Langmuir hole filling capacity (C' H) for CO 2 is very high compared to N 2 at both ambient and subambient temperatures. This trend was attributed to higher sorbed density of CO 2 at saturation in the micropores due to its transition from gas phase to the liquid phase at subambient temperatures. Significant increases in sorption selectivity as well as diffusion selectivity for CO 2 /N 2 going from ambient to subambient temperatures make CMS membranes a potential substitute for polymer membranes for CO 2 /N 2 separation. Highlights • First report demonstrating the performance of CMS membranes for CO 2 /N 2 separation at ambient and subambient temperatures. • 6FDA/BPDA-DAM defect free polymer precursors are used for CMS membranes preparation at 550 °C pyrolysis temperature. • CMS membranes show 4.5x higher CO 2 /N 2 selectivity at −20 °C than observed at 35 °C with ~ 33% loss in CO 2 permeance. • CMS membranes maintained their selectivity and productivity as the temperature was cycled between 35 °C and −20 °C. • High increase in sorption selectivity is playing major role at −20 °C due to the increase in sorbed density of CO 2. [ABSTRACT FROM AUTHOR]

Review: [synthesis and applications of Se-containing conjugated polymers for organic solar cells; 95 refs. [ABSTRACT FROM AUTHOR]

The thermally activated electrical conductivity and charge transfer properties of self-assembled naphthalene diimide molecule have been studied with N,N'di(hexadecyl)naphthalene tetracarboxylic diimide (HD-NDI) derivative. The self-assembly of HD-NDI has been resulted in one-dimensional large micron-size ribbons. The aggregate formation and self-assembling property have been extensively studied by absorption, fluorescence and X-ray diffraction analysis. Absorption and fluorescence measurements were taken in variety of solvents in fresh and aged samples, and the study suggested J-type aggregation for self-assembly formation. The electrical conductivity of self-assembled HD-NDI material was measured as a function of temperature where the conductivity increased with temperature and the highest conductivity (1 × 10 S/cm) was obtained at 250 °C. SEM images clearly show the formation of ribbons of micron size. Further the electron transport property of HD-NDI was also evaluated by SCLC method at room temperature by fabricating electron-only devices with annealing the film at ~ 200 °C. HD-NDI shows excellent electron mobility (1.8 × 10 cm V s) because of effective channel formation due to self-assembly of HD-NDI molecules, and this material may find potential application in variety of electronic devices. [ABSTRACT FROM AUTHOR]

The main objective of this study was to prepare a solid self-microemulsifying drug delivery system (S-SMEDDS) by spray drying liquid SMEDDS with an inert solid carrier Aerosil 200 to improve the dissolution rate and permeability of chlorthalidone (CTD). The liquid SMEDDS was composed of CTD, oleic acid, tween 20, and PEG 200. Preliminary screening was performed to select proper component combination. Solubility of CTD was determined in various vehicles. Ternary phase diagram for four series was constructed to delineate the boundaries of the nanoemulsion domain. Optimized S-SMEDDS (S3) was evaluated for dispersibility test (13.30 ± 0.95), percentage transmittance (99.50 ± 0.002), turbidity (260.43 ± 1.02), percent drug content (97.86 ± 0.56), droplet size (159.4), polydispersity index (PDI, 0.30), and zeta potential (−12.4). Solid-state characterization was done by scanning electron microscopy (SEM), differential scanning calorimetry, X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR). The XRD analysis confirmed that there was no crystalline CTD in the S-SMEDDS. SEM study revealed adsorption of liquid SMEDDS on Aerosil 200. In vitro drug release study was performed using water and 0.1N HCl as dissolution medium and compared with plain drug and marketed tablet Thaiklor TM 12.5, and marked increase in rate and extent of dissolution of S-SMEDDS was observed. Ex vivo intestinal permeability study revealed that diffusion of drug was significantly higher from S-SMEDDS than that of suspension of plain drug. The solid SMEDDS formulation was stable. In conclusion, the S-SMEDDS might be an encouraging strategy to improve the oral absorption of CTD. [ABSTRACT FROM PUBLISHER]

• Perylenediimide (PDI) derivatives bearing branched end groups have been designed and synthesized for their controlled self-assembly formation and tuning of energy levels. • On using these PDI derivatives as ETL better solar cell device performance as high as 5.7 (±0.1) % was achieved compared to their precursor PDI molecules with linear/short substituents. • Detailed study has been performed for the structure–property relationship for self-assembly behaviour, photophysical and charge transport properties. • The device data is studied experimentally as well as theoretically and it is observed that PDI derivatives forming J-type aggregates show better device properties in comparison to H-type aggregates. Although organic photovoltaics has witnessed significant growth in their power conversion efficiency still there is need to develop novel electron transport materials that can improve the electron extraction through energy level tuning. Perylenediimide (PDI) is one of the known n-type semiconductor which forms highly ordered self-assembled aggregates by intermolecular interactions. Considering the facile processability of these, herein we report perylenediimide (PDI) derivatives with branched end groups via Michael addition reaction. This work describes the synthesis of two PDI derivatives, i.e., MA-PDI-EDA and MA-PDI-PPD via two-step process and these were further studied for the effect of branched end groups on aggregation behaviour as well as its correlation with the opto-electronic properties. The self-assembling and charge transport properties of the synthesized molecules are fine tuned by branched imide substituent which allows improved performance of these materials as electron transport layer in organic solar cell devices in comparison to their PDI precursors. MA-PDI-EDA forming J-type aggregate showed improved power conversion efficiency in comparison to MA-PDI-PPD undergoing H-type aggregation. Ultrafast transient absorption spectroscopy was also performed for understanding the charge carrier dynamics in the two MA products. A complete rational for the observation is discussed using the theoretical fitting of device I-V characteristics. [ABSTRACT FROM AUTHOR]

The current work describes the Michael addition (MA) reaction between amine group appended NDI derivatives and α,β-unsaturated ketones (chalcones) with an aim to tune the optical and electrochemical properties of NDI derivatives via an easy and scalable synthesis method. Two NDI derivatives having aromatic (1) and aliphatic (2) amine N-imide substituents were synthesized and further used for the synthesis of MA products. The products were evaluated for their optical, electrochemical and transport properties. Aggregation behavior of the molecules was studied and established by absorption and emission spectroscopy. It is observed that NDIs and their respective MA derivatives (3 and 4) show strong aggregation behavior. Most interestingly the HOMO–LUMO energy levels in MA products were uplifted which is generally not achieved by imide-N substitutions. The driving force for intramolecular electron transfer was calculated from their first oxidation and reduction potentials indicating the formation of charge separated states. MA products also showed improved electron mobility compared to their NDI precursors. Intramolecular charge transfer interaction was established by fluorescence and femtosecond transient absorption spectroscopy (TAS). The materials have been studied for their use as electron transport layer (ETL) materials in inverted organic solar cells and an efficiency of 3% has been obtained. Overall, Michael addition reaction on NDI has resulted in effective tuning of optical properties, energy levels and transport properties without involving tedious multistep core substitution reactions. [ABSTRACT FROM AUTHOR]

• Synthesis of (E)−2-(3-cyano-5,5-dimethyl-4-styrylfuran-2(5H)-ylidene)malononitrile (S1), phenyl functionalized C 60 (S2) and furan functionalized C 60 (S3) is reported. • The electron mobility in S1, S2 and S3 was studied using space-charge limiting current (SCLC) model. • After thermal treatment at 70 °C, S1, S2 and S3 displayed a maximum electron mobility (μ e) of (1.39 ± 0.30) × 10−3, (1.3 ± 0.24) × 10−4 and (1.84 ± 0.26) × 10−3 cm2/V.s, respectively. • Conjoint molecular architecture of TCF and fullerene exhibits interesting photophysical and electrochemical an efficient charge transport properties. The charge mobility is an important property of organic optoelectronic materials. Fullerene (C 60) derivatives have been extensively used as electron acceptor materials in optoelectronics. However, the effect of structural modification of fullerene with furan moieties on its charge transport characteristics has rarely been studies. Herein, we synthesized (E)-2-(3-cyano-5,5-dimethyl-4-styrylfuran-2(5H)-ylidene)malononitrile (S1), phenyl functionalized C 60 (S2) and furan functionalized C 60 (S3) using S2 as a reactant. These compounds have been fully characterized by means of FTIR, 1H NMR, 13C NMR spectroscopy and MALDI-TOF spectrometry for their structure. The photophysical and electrochemical characteristics of S1, S2 and S3 were studied to understand the effect of structural architecture change of C 60 over redox and optical properties. The electron mobility in S1, S2 and S3 was studied using space-charge limiting current (SCLC) model where, S3 shows 18x higher mobility than the most used acceptor PB61BM. After thermal treatment at 70 °C, S1, S2 and S3 displayed a maximum electron mobility (μ e) of (1.39 ± 0.30) × 10−3, (1.3 ± 0.24) × 10−4 and (1.84 ± 0.26) × 10−3 cm2/V.s respectively. Further, computational method was employed to model the S1, S2 and S3 electronic structure and frontier electron transitions. Both HOMO and LUMO states drop by exactly the same amount upon structural change from S2 to S3 to give equal E g when calculated using B3LYP. This suggests that conjoint molecular architecture of TCF and fullerene exhibits interesting photophysical and electrochemical an efficient charge transport properties. [Display omitted] [ABSTRACT FROM AUTHOR]

• D-A-D triads type molecules synthesized using perylenediimde (PDI) bonded with naphthalenediimide (NDI) units via aliphatic (Triad 1) or aromatic (Triad 2) linker showed symmetry breaking charge separation (SB-CS). • SB-CS phenomenon is studied using photoluminescence, time resolved fluorescence, transient absorption spectroscopy techniques. • The organic solar cell fabricated using Triad 2 resulted in better device performance compared to Triad 1 due to increased open circuit voltage (V oc) because of more effective SB-CS state. • Triad 2 shows overall better power conversion efficiency of 4.4 % with FF 67 % in comparison to Triad 1. Multichromophoric D-A-D triads synthesized using perylenediimde (PDI) bonded with naphthalenediimide (NDI) units via aliphatic (Triad 1) or aromatic (Triad 2) linker is studied for symmetry breaking charge separation (SB-CS) by selective excitation of the NDI/PDI chromophores. NDI chromophore on excitation transfers electron to PDI chromophore and type of linker played crucial role in stability of generated CS state. Photoluminescence, time resolved fluorescense and transient absorption spectroscopy tools have been used to study the phenomenon. The optical as well as electrochemical study confirmed intramolecular electron transfer from NDI to PDI chromophore. Stable SB-CS state formation is directly resulted in increased open circuit voltage (V oc) of Triad 2 based organic solar cell devices. The selective excitation of chromophoric center and SB-CS in D-A-D type triad is the demand of present electronic device for the formation of long lived charge carrier. [ABSTRACT FROM AUTHOR]

Previous studies have shown influence of aliphatic side chain length and type on the transport properties of naphthalenediimide (NDI) materials by affecting molecular arrangement. There is lack of comparative study on the presence or absence of unsaturation in side chain and its effect on optical and electronic properties of NDI. The present work focuses on the structure–property relationship of four NDI derivatives bearing octyl (C8, OctA-NDI), hexadecyl (C16, HD-NDI), octadecyl (C18, ODA-NDI) and oleyl (C18-un, unsaturated, OLA-NDI) chain on imide-nitrogen. The self-assembling behaviour of the molecules is studied in concentrated solutions as fresh and aged samples in four different solvents by absorbance and emission spectroscopy. With increase in alkyl chain length, the aggregation behaviour is observed to increase. Very interestingly introduction of unsaturation in side chain reduces aggregation and restores the monomeric properties. Self-assembled microstructures formation was studied by scanning electron microscopy where all the four materials show different types of self-assembly formation. Finally, we compared the thermally activated electron conductivity and electron mobility of NDI derivatives, where also the side chain structure clearly influences the electron transport. Electron mobility decreases on increasing chain length from C8 to C18 and again increases in C18-un. A rationale for the structure–property relationship has been given based on the molecular packing and intermolecular π–π interactions. This study contributes significantly towards designing new NDI derivatives bearing long side chains with hampered aggregation for niche applications. [ABSTRACT FROM AUTHOR]

In this work, we report the adsorption studies of dyes using as- prepared doped poly(3,4-ethylenedioxythiophene) (PEDOT). The conjugated polymer PEDOT was prepared by the solid-state polymerization method and used as an effective adsorbent for the removal of various dyes from aqueous solution. It was found that the as -prepared PEDOT adsorbs selective anionic dyes, whereas no significant adsorption was observed for cationic dyes. The effect of concentration of eriochrome black T (EBT) dye on time-dependent adsorption was studied. Like doped PEDOT, de-doped PEDOT was examined with different concentrations of EBT dye solutions and observed poor adsorption. The adsorption kinetics and isotherms for doped and de-doped PEDOT were studied. The morphology and elemental composition of doped PEDOT before and after adsorption were analyzed by scanning electron microscopy and energy-dispersive X-ray, respectively. Further, the effectiveness of as -prepared doped polymer PEDOT as an adsorbent for EBT dye from organic solvents (ethanol, DMSO, acetonitrile and DMF) was carried out. [Display omitted] • Solid-state synthesized PEDOT was used as an adsorbent for organic dyes removal. • Doped PEDOT shows selective adsorption for anionic dyes in an aqueous medium. • Kinetics models and isotherms of the adsorption process were studied. • Different organic solvents were examined for adsorption of an anionic dye. [ABSTRACT FROM AUTHOR]

We designed and synthesized a series of naphthalenediimide (NDI) derivatives through core-substitution (coded as cNDI) with various number of 2-ethyl-hexylamine (EHA) chains at different positions. The molecular structure of cNDI derivatives such as cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA bearing one, two, three and four 2-ethyl-hexylamine chains, respectively, was confirmed by different spectroscopic techniques such as FTIR, 1H-NMR, 13C-NMR spectroscopy and mass spectrometry. Interestingly, the incorporation of different numbers of 2-ethyl-hexylamine on electron-deficient cNDI yields diverse photophysical and electrochemical properties. The change in the number of alkyl chains on the NDI core significantly influences the redox properties and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. The changes in the morphology of the spin-coated films before and after annealing are reorganized differently depending on the number of 2-ethyl-hexylamine topology proved by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The electron mobility of cNDIs was examined by following the standard protocol of the space-charge limiting current (SCLC) method. The NDI derivatives bearing various number of 2-ethyl-hexylamine chains at the NDI core after thermal treatment at 170 °C exhibited very good electron mobility of the order of 10−6 to 10−4 cm2 V−1 s−1. The observed electron mobility trends depend not only on the number of 2-ethyl-hexylamine substituents but also on the changes in thin-film morphology. [ABSTRACT FROM AUTHOR]

This article investigates the performance of the p-Bi2Te3/n-Si heterostructure diode with different metallic contacts. The heterostructure was realized by the thermal coating of a topological insulator (TI) Bi2Te3 film on n-Si. The crystal phase study of the Bi2Te3 film was done by X-ray diffraction (XRD), while the microstructural and morphological study was done by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The CV characterization for the diode showed almost no hysteresis except for the gold (Au) contact device, which could be due to the trapping of electrons at the interface. The current–voltage (IV) measurement was done in the dark, which confirmed the formation of p-n diode heterostructure. Diode having platinum (Pt) metallic contact exhibited the best ideality factor (n = 7.00), while the diode with gold (Au) contact closely followed it (n = 8.91). The best figure of merit (FOM≈2.588 was observed for Pt contact device with the maximum rectification ratio (RR ~ 442 and majority charge carrier concentration (NA) = 1.47 × 1025/cm3. The experimental results of I-V for different contact devices were further simulated using the two-diode model and various diode parameters were extracted. The current density–voltage (JV) and local ideality factor–voltage (nV) plots were studied to find the ideality factor and recombination current (J02) for different metallic contact devices. The Pt contact diode was found to be nearest to the ideal behavior of a diode exhibiting the least recombination current (J02) = 9.7 × 10−17 A/m2. [ABSTRACT FROM AUTHOR]

Fullerene derivatives (C60 and C70) have been widely used in excitonic solar cells due to their exceptional electron accepting properties and low reorganization energies. In recent years, a wide variety of fullerene-based n-type materials have been developed, showing tremendous potential in the field of organic photovoltaics. However, only a few studies have been performed on heteroatom bearing methanofullerenes and their opto-electronic properties for use as n-type organic semiconductor materials. In the present study, we report the synthesis of two mono-substituted methanofullerene derivatives, i.e., C60-Th (Product 1) and C60-TPA (Product 2), with a heteroatom (S and N, respectively) in the exohedral chain attached via an ethylene linker to the cyclopropane ring, and a comprehensive study of their photophysical and electrochemical properties. The methanofullerene derivatives have been synthesized using an amine-assisted cycloaddition (AACA) reaction method. The structures of the synthesized products were established via different spectroscopic techniques. Reasonable quenching efficiencies were observed with respect to the fluorescence emission in mixtures with the donor polymer P3HT using both methanofullerenes. The electron transport properties were evaluated through fabricating electron-only devices, and 10 and 6 times higher mobilities were found compared to PC61BM for Products 1 and 2, respectively. Finally, the charge transfer properties were evaluated in mixtures with P3HT via transient absorption spectroscopy to study the ultrafast charge separation and formation of long-lived charge-separated states. The study suggests that both the products show excellent electron transport properties and the formation of longer-lived charge-separated states in mixtures with the donor polymer for use as n-type materials for organic solar cells. [ABSTRACT FROM AUTHOR]

Fullerene–porphyrin dyad system has gained increasing interest because of not only their interesting optoelectronic properties but also their applications in single-material organic solar cells. In the present work, two non-metallated fullerene–porphyrin dyads are prepared, viz, H2P1-C60 (dyad I) and H2P2-C60 (dyad II), where the modes of attachment on fullerene are different, i.e. via 1,3-dipolar cyclopropanation reaction in dyad I and Prato reaction in dyad II. We compare the photophysical and thermally activated conducting properties of these two non-metallated dyads in solution as well as in film to establish the better mode of attachment for dyad preparation with exotic properties. Both the dyads are structurally characterized by FT-IR, NMR and HRMS. Photophysical studies reveal that for dyad II, the reaction rate of charge separation is much higher than for dyad I (0.62 × 109 s−1vs. 0.32 × 109 s−1) in nonpolar solvent. Moreover, dyad II shows higher quenching of porphyrin emission than dyad I (90% vs. 70%) due to faster deactivation of singlet excited state by photoinduced charge transfer between porphyrin and fullerene. The reaction rate for charge transfer (kET(CS)) for dyad II is found to be maximum with lowest activation energy value as compared to dyad I. Excited-state electronic interactions in solution as well as in film have been studied by transient absorption spectroscopy to identify charge separated states. Finally, both the dyads are tested for their thermally activated electrical conductivity where dyad II shows an increase in conductivity with increase in temperature, which is reversible. Thus, dyad II is found to be an excellent material with interesting photophysical and electronic properties that can be beneficial in various applications such as organic solar cells and sensors. [ABSTRACT FROM AUTHOR]

Single material organic solar cells become an interesting area of research to overcome the challenges with efficient charge separation efficiencies in conventional organic solar cells. In this article, we have synthesized nonmetallated and metallated porphyrin-fullerene dyad materials (H2P-C60 and ZnP-C60, respectively) with simple structure, comprehensively studied their charge transfer mechanism, and established a proof of concept that nonmetallated porphyrin-fullerene dyads are better candidates to be used in organic solar cells compared with metallated dyads. Absorption and electrochemical analysis revealed the ground state electronic interactions between donor-acceptor moieties in both types of dyads. Driving force (−ΔGoET) for intramolecular electron transfer process was calculated by first oxidation and reduction potentials of dyads. The excited state electronic interactions were characterized by time-resolved fluorescence and pump-probe transient absorption experiments. Strong fluorescence quenching of porphyrin along with reduced lifetimes in dyads due to deactivation of singlet excited states by photoinduced charge transfer process between porphyrin/Zn-porphyrin core and fullerene in different polarity solvents was observed. Transient absorption spectroscopy was also applied to identify the transient spectral features, ie, cationic (H2P+/ZnP+) and anionic (C60−) radicals formed because of the charge separation in both types of dyads. Finally, organic solar cell device was also fabricated using the dyads. We obtained higher Voc, Jsc, and fill factor in single material organic solar cell using H2P-C60 compared to previous reports. [ABSTRACT FROM AUTHOR]

[Display omitted] • The p-TlBiSe 2 is an exotic topological insulator with less defect and disordered state, has considerable band gap and potential in spintronics and photo electric devices. • The p-TlBiSe 2 / n -Si heterojunction will synergize the transport property and will open a new dimension for the Si based optical industries. • Our manuscript contains very significant work in the area of heterojunction device fabrications with topological insulators and Si. We realized the heterostructure of quasi-2D-topological insulators films and n -Si for the formation of the p-n diode. • The good rectification ratio (RR ∼ 718 at ± 3 V) and figure of merit (FOM) in p-TlBiSe 2 / n -Si heterojunction for switching and other electronics applications. • The ultrafast measurements of p-TlBiSe 2 / n -Si heterojunction showed optical excitation in TlBiSe 2 with a strong modification of exciton transitions in Si. • Evidence of efficient charge separation in photoexcited p-TlBiSe 2 / n -Si heterojunction due to the presence of the charge state (CT). • The p-TlBiSe 2 / n -Si heterojunction has shown good responsivity and broadband photo detectivity from visible to near-infrared region in dual quadrants. • The 2-diode simulation is used to study the devices for various detrimental mechanisms such as recombination by studying the Current density- Voltage (J - V) and ideality factor-Voltage (n - V) curve. The study gives important insight into the optimization of devices for solar cells. The work presents a study of quasi-2D thin topological insulator film of TlBiSe 2 and its heterojunction TlBiSe 2 /Glass and TlBiSe 2 /Si by thermal coating. The vibrational modes were identified in both the heterojunctions using Raman spectroscopy with the identification of the surface phonon mode (SPM) in the TlBiSe 2 /Si heterojunction. Ultrafast dynamics were studied for the relaxation dynamics of the charge carriers in these heterojunctions. The study identified the interface phenomenon in the form of charge states (CT) in TlBiSe 2 /Si p-n heterojunction. The p-TlBiSe 2 / n -Si heterojunction showed good p-n diode characteristics with a rectification ratio under the dark. Its optical response was studied by varying optical power (2.37–3.78 µW) and wavelength (500–1900 nm). It showed excellent photoresponse in the visible to near-infrared (NIR) range which peaks at 900 nm wavelength in both forward as well reverse bias. The explanation of its optical and electrical performance was modeled in terms of band structure, surface states, and interface phenomenon. The study is important in terms of the implementation of next-generation topological insulator-based photodetectors. [ABSTRACT FROM AUTHOR]

New methanofullerene derivatives have been synthesized and characterized for their electron transport properties. Two new methanofullerenes (PC61BP & HC61NP) have been synthesized by using our reported amine assisted cycloaddition reaction (AACA) method in good yield. PC61BM is also synthesized by using the AACA method for comparison of properties. PC61BP has phenyl group and butyric acid pentyl ester substituents on the C(61) bridging carbon of the cyclopropane ring on the fullerene. HC61NP has a completely different structure where the C(61) bridging carbon is bonded to a proton and a 2-nitro cinnamyl group. Both the products have been well characterized by FTIR, UV-vis absorption spectroscopy and NMR for their structures. Their electrochemical properties have been evaluated by cyclic voltammetry. Finally, the electron mobilities of the materials have been calculated at room temperature by preparing electron-only devices. PC61BP shows the highest mobility compared to HC61NP and PC61BM and proves to be a promising acceptor material for organic solar cells. [ABSTRACT FROM AUTHOR]

Background: To evaluate the clinical validity of genome-wide oligonucleotide array comparative genomic hybridization (aCGH) for detecting somatic abnormalities, we have applied this genomic analysis to 30 cases (13 MDS and 17 AML) with clonal chromosomal abnormalities detected in more than 50% of analyzed metaphase cells. Results: The aCGH detected all numerical chromosomal gains and losses from the mainline clones and 113 copy number alterations (CNAs) ranging from 0.257 to 102.519 megabases (Mb). Clinically significant recurrent deletions of 5q (involving the RPS14 gene), 12p12.3 (ETV6 gene), 17p13 (TP53 gene), 17q11.2 (NF1 gene) and 20q, double minutes containing the MYC gene and segmental amplification involving the MLL gene were further characterized with defined breakpoints and gene contents. Genomic features of microdeletions at 17q11.2 were confirmed by FISH using targeted BAC clones. The aCGH also defined break points in a derivative chromosome 6, der(6)t(3;6) (q21.3;p22.2), and an isodicentric X chromosome. However, chromosomally observed sideline clonal abnormalities in five cases were not detected by aCGH. Conclusions: Our data indicated that an integrated cytogenomic analysis will be a better diagnostic scheme to delineate genomic contents of chromosomal and cryptic abnormalities in patients with MDS and AML. An evidence-based approach to interpret somatic genomic findings was proposed. [ABSTRACT FROM AUTHOR]

In this report, a systematic study of mixed polymorph and binary integration of MoO 3 multilayer structures has been given. The spin-coated multilayer nanorods (hexagonal and orthorhombic) of MoO 3 are fabricatedon glass substrates and TiO 2 coated glass substrate at different temperatures, i.e., 300 °C and 500 °C. The microstructure and surface analysis of the deposited films were characterized by X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The optical properties of the films were characterized by UV–visible absorption spectrophotoscopy and theoretical analysis of the transmittance data. The optical bandgap falls between the wavelength range from 225 nm to 310 nm. Due to the optical bandgap in UV region and good transmission properties in the visible region, the fabricated thin-film structures may be developed as selective wavelength optical filters, which can control the unwanted distribution of UV radiation. Image 1 • A new type of one dimensional selective wavelength filter developed experimentally. • The mixed polymorph and binary integration of MoO 3 material used. • The optical bandgap is around "225 nm < λ < 310 nm" which is good to block UV radiation. • This material structure is also showing structure colour changing properties. [ABSTRACT FROM AUTHOR]

One dimensional (1D) transition metal oxide nano-structured materials have high possibilities in the field of sensor applications. In the current work, we have investigated gas sensing response of the less explored hexagonal-Molybdenum Oxide (h-MoO 3) for ammonia (NH 3) gas. We have synthesized h-MoO 3 nano-rods by facile chemical bath technique (CBT). To fabricate sensors, thin films were deposited on glass substrates using spin coating technique. Change in resistance of the film on NH 3 exposure was recorded with time. The gas sensing response was measured at different concentration levels of NH 3 ranging from 5 ppm to 100 ppm at 200 °C. We observed comparatively high sensing percentage for low to high concentration of NH 3 gas at moderate operating temperature. h-MoO 3 nano-structured rods based ammonia sensors lend a promising prospective in industrial applications like fertilizer, refrigeration industries etc. [ABSTRACT FROM AUTHOR]