MOFite: A High-Density Lithiophilic and Scalable Metal-Organic Framework Anode for Rechargeable Lithium-Ion Battery.

Developing an anode material that has better performance efficiency than commercial graphite while keeping the features of economic scalability and environmental safety is highly desirable yet challenging. MOFs are a promising addition to the ongoing efforts, however, the relatively poor performance, chemical instability, and large-scale economic production of efficiency-proven pristine MOFs restrict their utility in real-life energy storage applications. Furthermore, hierarchical porosity for lucid mass diffusion, high-density lithiophilic sites are some of the structural parameters for improving the electrode performance.

Structural and optical properties of phosphorous doped nanocrystalline silicon deposited using a VHF PECVD process for silicon heterojunction solar cells and optimization of a simple p-n junction cell using SCAP-1D tool.

Initially hydrogenated silicon (Si:H) thin films have been deposited using a plasma-enhanced chemical vapor deposition technique (PECVD) using silane (SiH) as a precursor gas diluted in an inert gas argon (Ar) environment. Subsequently phosphine gas (PH) was used as the n-type dopant and the deposition was carried out at a fixed substrate temperature of 200 °C. The PH flow rate was varied in the range of 0-1 sccm.

D-A-D-based Unsymmetrical Thiosquaraine Dye for the Dye-Sensitized Solar Cells.

In dye-sensitized solar cell, modulating the electronic properties of the sensitizer by varying the donor, π-spacer, acceptor and anchoring groups help optimizing the structure of the dye for better device performance. Here, a donor-acceptor-donor-based unsymmetrical thiosquaraine sensitizer (SQ5S) has been designed and synthesized. Photophysical, electrochemical, theoretical and photovoltaic characterizations of SQ5S dye have been compared with its oxygen analog, SQ5.

Solvent-Dependent Functional Aggregates of Unsymmetrical Squaraine Dyes on TiO Surface for Dye-Sensitized Solar Cells.

Alkyl group wrapped donor-acceptor-donor (D-A-D) based unsymmetrical squaraine dyes , , and were used to evaluate the effect of sensitizing solvents on dye-sensitized solar cell (DSSC) efficiency. A drastic change in DSSC efficiency was observed when the photo-anodes were sensitized in acetonitrile (bad solvent when considering dye solubility) and chloroform (good solvent) with an Iodolyte (I/I) electrolyte. The DSSC device sensitized with squaraine dyes in acetonitrile showed better photovoltaic performance with enhanced photocurrent generation and photovoltage compared to the device sensitized in chloroform.

Alkyl-Group-Wrapped Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells: Branched Alkyl Chains Modulate the Aggregation of Dyes and Charge Recombination Processes.

Electron transfer processes at the interfaces dictate the factors that improve the photovoltaic parameters, such as open-circuit voltage () and short-circuit current (), of a dye-sensitized solar cell device, besides selection of a set of suitable anode, dye, electrolyte, and cathode materials. An inefficient charge injection process at the dye-TiO interface and charge recombination at the TiO-dye/electrolyte interface have detrimental effects on improving both and . Hence, tailoring the factors that govern the improvement of and will be an ideal approach to get the desired sensitizers with good device efficiencies.

Interfacial Modification of Photoanode|Electrolyte Interface Using Oleic Acid Enhancing the Efficiency of Dye-Sensitized Solar Cells.

Dye-sensitized solar cells (DSSCs) are useful devices in converting renewable solar energy into electrical energy. In DSSCs, the triiodide reduction at the surface of TiO is one of the detrimental processes that limit the realization of high efficiencies of the device. To alleviate the active sites available on the semiconductor surface for this detrimental process, the interfacial modification of the dye-adsorbed TiO|electrolyte interface has been attempted by coadsorption of oleic acid (OA) over the TiO surface.

Homo- and Heterodimeric Dyes for Dye-Sensitized Solar Cells: Panchromatic Light Absorption and Modulated Open Circuit Potential.

The design of dyes for panchromatic light absorption has attracted much attention in the field of dye-sensitized solar cells (DSSCs). An approach to enhance panchromatic light absorption utilizes mixtures of complementary light-absorbing dyes as well as dyes with specific anchoring groups that facilitate interfacial charge transfer with TiO . Dipole-dipole interactions between the dye molecules on the surface broaden the spectrum, which results in decreased DSSC device performance.

Modulated photochemical reactivities of O-acetylated (3',5'-dimethoxyphenyl)heteroaryl acyloin derivatives under direct irradiation and photo-induced electron transfer conditions.

3',5'-Dimethoxybenzoin esters are important photoremovable protecting groups which form 2-phenylbenzofuran derivatives upon photo-release. We utilized a similar concept to test a photochemical method of installing a benzofuran moiety to the conjugated backbone by subjecting O-acetylated (3',5'-dimethylphenyl)heteroaryl acyloin derivatives through direct photo irradiation and a photo-induced electron transfer reaction. These photochemical methods were explored for a variety of heteroaromatic substrates appended on the ketone part of the O-acetylated cross-acyloin derivatives.

Self-Assembly of Cis-Configured Squaraine Dyes at the TiO-Dye Interface: Far-Red Active Dyes for Dye-Sensitized Solar Cells.

To synergize both steric and electronic factors in designing the dyes for dye-sensitized solar cells, a series of cis-configured unsymmetrical squaraine dyes P11-P15 with suitably functionalized alkyl groups and squaric acid units containing the electron-withdrawing groups were synthesized, respectively. These dyes capture the importance of (i) the effect and position of branched alkyl groups, (ii) mono- and di-anchoring groups containing dyes, and (iii) further appending the alkyl groups through the cyanoester vinyl unit on the central squaric acid units of D-A-D-based cis-configured squaraine dyes. All the above factors govern the controlled self-assembly of the dyes on the TiO surface which helps to broaden the absorption profile of the dyes with an increased energy-harvesting process.

Significant enhancement in thermoelectric performance of nanostructured higher manganese silicides synthesized employing a melt spinning technique.

The limited thermoelectric performance of p-type Higher Manganese Silicides (HMS) in terms of their low figure-of-merit (ZT), which is far below unity, is the main bottle-neck for realising an efficient HMS based thermoelectric generator, which has been recognized as the most promising material for harnessing waste-heat in the mid-temperature range, owing to its thermal stability, earth-abundant and environmentally friendly nature of its constituent elements. We report a significant enhancement in the thermoelectric performance of nanostructured HMS synthesized using rapid solidification by optimizing the cooling rates during melt-spinning followed by spark plasma sintering of the resulting melt-spun ribbons. By employing this experimental strategy, an unprecedented ZT ∼ 0.

A Convenient Synthesis Route for CoO Hollow Microspheres and Their Application as a High Performing Anode in Li-Ion Batteries.

A new, rapid, and cost-effective method for synthesizing hollow microspheres (HMSs) of cobalt oxide (CoO) using the phloroglucinol-formaldehyde gel route is reported here. Further, the synthesized hollow CoO microspheres were investigated as an anode material for Li-ion batteries. The CoO hollow spheres exhibited excellent electrochemical performance and cycling stability, for example, a capacity of 915 mA h g was obtained at 1 C rate over 350 cycles.

Orthogonally Functionalized Donor/Acceptor Homo- and Heterodimeric Dyes for Dye-Sensitized Solar Cells: An Approach to Introduce Panchromaticity and Control the Charge Recombination.

Organic dyes possessing conjugated π-framework forms closely packed monolayers on photoanode in dye-sensitized solar cell (DSSC), because of the limitation to control the orientation and the extend of intermolecular π-π interaction, self-aggregation of dyes leads to reduced cell performance. In this report, a series of homodimeric (D-D and D-D) and heterodimeric (D-D and D-D) donor/acceptor (D/A) dyes containing spiroBiProDOT π-spacer were designed and synthesized by utilizing Pd-catalyzed direct arylation reaction and correlates the device performance with monomeric dyes (D and D). Both the thiophenes (π-spacer) of spiroBiProDOT were functionalized with same or different donor groups which led to homodimeric and heterodimeric chromophores in a single sensitizer.

Enhancement in thermoelectric performance of SiGe nanoalloys dispersed with SiC nanoparticles.

SiGe is one of the most widely used thermoelectric materials for radioisotope thermoelectric generator applications for harnessing waste-heat at high temperatures. In the present study, we report a simple experimental strategy for enhancing the thermoelectric and mechanical properties of n-type SiGe nanoalloys by dispersing SiC nanoparticles in a SiGe nanoalloy matrix. This strategy yielded a high value of figure-of-merit (ZT) of ∼1.

Interplay between π-Bridges and Positions of Branched Alkyl Groups of Unsymmetrical D-A-D-π-A Squaraines in Dye-Sensitized Solar Cells: Mode of Dye Anchoring and the Charge Transfer Process at the TiO/Dye/Electrolyte Interface.

Far-red-absorbing squaraines possessing high molar absorptivity (>10 M cm) are being attracted as high-efficiency chromophores in dye-sensitized solar cells (DSSCs). A series of donor-acceptor-donor-π spacer-acceptor (D-A-D-π-A) unsymmetrical squaraines, PSQ1-5, with indoline donor and squaric/cyanoacetic acid acceptor units, were designed for sensitized solar cells. For extending the absorption toward the near-infrared region (NIR) and controlling the orientation on the TiO surface, benzene (PSQ1 and PSQ2) and thiophene (PSQ3-5) π-spacers and out-of-plane branched alkyl groups at the indoline that are away (PSQ1, PSQ3, and PSQ5) or near (PSQ2 and PSQ4) the anchoring group, respectively, were introduced.

An interaction potential to study the thermal structure evolution of a thermoelectric material: β-Cu Se.

An interaction potential model has been developed, for the first time, for β-Cu Se using the ab initio derived data. The structure and elastic constants of β-Cu Se using the derived force-field are within a few percent of DFT derived structure and elastic constants and reported experimental structure. The derived force-field also shows remarkable ability to reproduce temperature dependent behavior of the specific heat and thermal expansion coefficient.

Panchromatic Sensitizer for Dye-Sensitized Solar Cells: Unsymmetrical Squaraine Dyes Incorporating Benzodithiophene π-Spacer with Alkyl Chains to Extend Conjugation, Control the Dye Assembly on TiO, and Retard Charge Recombination.

Metal-free near-infrared (NIR) active unsymmetrical squaraine dyes, RSQ1 and RSQ2, with benzodithiophene (BDT) π-spacer and cyanoacrylic acid acceptor were synthesized by utilizing palladium catalyzed direct (hetero)arylation reaction. Methyl and 2-ethylhexyl groups were strategically placed at the BDT unit for RSQ1 and RSQ2, respectively, to investigate the effect of alkylated π-spacer on dye aggregation on the TiO surface and recombination reactions at TiO/dye/electrolyte interface. These dyes have strong absorption (ε > 10 M cm) in near-infrared (NIR) region and exhibit similar optical and electrochemical properties as they have same conjugated framework.

Effect of Out-of-Plane Alkyl Group's Position in Dye-Sensitized Solar Cell Efficiency: A Structure-Property Relationship Utilizing Indoline-Based Unsymmetrical Squaraine Dyes.

Squaraine dyes are promising chromophores to harvest visible and near-infrared (NIR) photons. A series of indoline-based unsymmetrical squaraine (SQ) dyes that contain alkyl chains at sp C- and N- atoms of indoline moieties with a carboxylic acid anchoring group were synthesized. The optical and electrochemical properties of the SQ dyes in solution were nearly identical as there was no change in the D-A-D SQ framework; however, remarkable changes with respect to the power conversion efficiencies (PCE) were observed depending upon the position of alkyl groups in the dye.

Flexible Microsupercapacitors Using Silk and Cotton Substrates.

Flexible microsupercapacitors (MSCs) are needed to power ultrasmall wearable electronic devices. Silk cocoons comprise microfibers of silk, which is an attractive natural resource to fabricate MSCs. These fibers are insulators; hence, they must be converted to conducting surfaces.

Selenium-Containing Fused Bicyclic Heterocycle Diselenolodiselenole: Field Effect Transistor Study and Structure-Property Relationship.

The first application of the diselenolodiselenole (C4Se4) heterocycle as an active organic field effect transistor materials is demonstrated here. C4Se4 derivatives (2a-2d) were obtained by using a newly developed straightforward diselenocyclization protocol, which includes the reaction of diynes with selenium powder at elevated temperature. C4Se4 derivatives exhibit strong donor characteristics and planar structure (except 2d).

A Highly Selective Chemosensor for Cyanide Derived from a Formyl-Functionalized Phosphorescent Iridium(III) Complex.

A new phosphorescent iridium(III) complex, bis[2',6'-difluorophenyl-4-formylpyridinato-N,C4']iridium(III) (picolinate) (IrC), was synthesized, fully characterized by various spectroscopic techniques, and utilized for the detection of CN(-) on the basis of the widely known hypothesis of the formation of cyanohydrins. The solid-state structure of the developed IrC was authenticated by single-crystal X-ray diffraction. Notably, the iridium(III) complex exhibits intense red phosphorescence in the solid state at 298 K (ΦPL = 0.

Reduced graphene oxide anchored Cu(OH)2 as a high performance electrochemical supercapacitor.

Developing new materials for electrochemical supercapacitors with higher energy density has recently gained tremendous impetus in the context of effective utilization of renewable energy. Herein, we report a simple one-pot synthesis of bundled nanorods of Cu(OH)2 embedded in a matrix of reduced graphene oxide (Cu(OH)2@RGO) under mild hydrothermal conditions of 80 °C for 1 h. The synthesized material shows a high BET surface area of 78.

The role of nanoscale defect features in enhancing the thermoelectric performance of p-type nanostructured SiGe alloys.

Despite SiGe being one of the most widely studied thermoelectric materials owing to its application in radioisotope thermoelectric generators (RTG), the thermoelectric figure-of merit (ZT) of p-type SiGe is still quite low, resulting in poor device efficiencies. In the present study, we report a substantial enhancement in ZT∼ 1.2 at 900 °C for p-type nanostructured Si80Ge20 alloys by creating several types of defect features within the Si80Ge20 nanostructured matrix in a spectrum of nano to meso-scale dimensions during its nanostructuring, by employing mechanical alloying followed by spark plasma sintering.

Polymer-Polymer Förster Resonance Energy Transfer Significantly Boosts the Power Conversion Efficiency of Bulk-Heterojunction Solar Cells.

Optically resonant donor polymers can exploit a wider range of the solar spectrum effectively without a complicated tandem design in an organic solar cell. Ultrafast Förster resonance energy transfer (FRET) in a polymer-polymer system that significantly improves the power conversion efficiency in bulk heterojunction polymer solar cells from 6.8% to 8.

An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals.

In this work, we have demonstrated the structural and optoelectronic properties of the surface of ternary/quaternary (CISe/CIGSe/CZTSe) chalcopyrite nanocrystallites passivated by tri-n-octylphosphine-oxide (TOPO) and tri-n-octylphosphine (TOP) and compared their charge transfer characteristics in the respective polymer: chalcopyrite nanocomposites by dispersing them in poly(3-hexylthiophene) polymer. It has been found that CZTSe nanocrystallites due to their high crystallinity and well-ordered 3-dimensional network in its pristine form exhibit a higher steric- and photo-stability, resistance against coagulation and homogeneity compared to the CISe and CIGSe counterparts. Moreover, CZTSe nanocrystallites display efficient photoluminescence quenching as evident from the high value of the Stern-Volmer quenching constant (K SV) and eventually higher charge transfer efficiency in their respective polymer P3HT:CZTSe composites.

Cu-Ni nanoparticle-decorated graphene based photodetector.

We report a simple and straight forward approach for the synthesis of Cu-Ni graphene hybrid nano-composites. These nano-composites have been characterized using AFM, XRD, FTIR spectroscopy and HRTEM. The characterization data clearly shows uniform decoration of Cu-Ni nanoparticles on graphene layers.