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Efficient separation of charges and their mobility are key challenges in metal–organic-framework (MOF) based devices. In the present study, thin films of cobalt-based metal organic frameworks (MOFs) are synthesized using a layer-by-layer technique, and their electrical/optoelectronic properties are studied. The as-prepared MOF films show electrically insulating behavior, which after hole doping demonstrate p-type conduction behaviour. The measured HOMO–LUMO energy states of the MOF films are found to be well matched for sensitizing TiO2, and the photoluminescence quenching experiment demonstrates a facile photoelectron transfer path from the doped frameworks to TiO2. Consequently, the doped MOFs are employed successfully as light harvesting and charge transporting active layers in a fully devised TiO2-based solar cell. Two different organic ligands viz., benzene dicarboxylic acid and naphthalenedicarboxylic acid are used to synthesize two kinds of Co–MOFs having different geometrical dimensions of unit cells and pores, and their influence on hole doping and charge transportation is studied. Under optimized conditions, the Co–MOF based device demonstrates a solar-to-electric energy conversion efficiency of 1.12% with a short circuit current of 2.56 mA cm−2, showing promising future prospects of the application of Co–MOFs in photovoltaic devices. Further, the photovoltaic performance of the Co–MOF based device is comparatively studied with that of the previously reported Cu–MOF and Ru–MOF based similar devices, and the influence of different metal centers of MOFs on their light harvesting performance is discussed. [ABSTRACT FROM AUTHOR]

In a new heterojunction solar cell employing CH3NH3PbBr3 (MAPbBr3) as the light absorber, we found that the introduction of a carboxylate monolayer on the mesoporous TiO2 surfaces significantly enhances JSC as well as VOC. In particular, the presence of a bromoacetate monolayer at the interface of TiO2/MAPbBr3 remarkably increases the photovoltaic conversion efficiency (PCE) from 2.65% to 5.57% with JSC of 5.411 mA cm−2, VOC of 1.372 V, and FF of 0.75. Time-resolved photoluminescence measurements indicate that the presence of the interfacial carboxylate groups expedites electron injection from MAPbBr3 to TiO2. Furthermore, according to pulsed light-induced transient measurements (PLITM) of photocurrent analysis, the lifetime of photoinjected electrons (τe) in the TiO2 conduction band (CB) significantly increases with the passivation of the interface, implying the suppression of charge recombination as well. [ABSTRACT FROM AUTHOR]

Based on a coordination chemistry approach, the present work reports on the synthesis of thin films of various cobalt hydroxycarbonate nanostructures such as nanobeams, nanoneedles, and bending nanorods using three different cobalt precursors viz. Cl−, NO3− and CH3COO−. After pyrolysis in air, the hydroxycarbonate nanostructures are transferred into 1-D arrays of Co3O4 nanorods. The obtained 1-D Co3O4 nanostructures are then transformed into the corresponding analogous shaped 1-D arrays of porous cobalt sulfide (CoS1.0365) nanostructures using a wet chemical transformation method based on an ion exchange approach. The nanostructured films before and after the ion exchange reaction are characterized using field emission electron scanning microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), and inductively coupled plasma mass spectroscopy (ICP-MS) measurements. As a proof-of-concept demonstration for the application, various shaped CoS1.0365 nanorod films synthesized are investigated as a Pt-free counter electrode in dye-sensitized-solar cells (DSSCs). The influence of three different counter anions of the cobalt precursors on the structural, textural, and morphological aspects, and thereby their influence on electronic and electrochemical properties, has been investigated. A correlation among electrical conductivity, charge transfer resistance and electrocatalytic performance of various CoS1.0365 nanorod films obtained from different cobalt precursors has been established. Among the various nanostructures, the thicker nanorod film synthesized using a chloride precursor has demonstrated the best electrocatalytic behavior toward triiodide reduction, which led to a short circuit current density of 18.04 mA cm−2 and energy conversion efficiency of 7.4% of the DSSC. This photovoltaic performance is highly competitive to a current density of 18.26 mA cm−2 and energy conversion efficiency of 7.7% exhibited by the standard Pt counter electrode. [ABSTRACT FROM AUTHOR]

Chemical bath deposition is an attractive technique toform single-and multilayered metal oxide/chalcogenide films on electrode surfaces.However, the occurrence of desorption and/or ion-exchange reactionduring subsequent chemical bath deposition has so far limited preparationof multilayered metal oxide/chalcogenide films. In this paper, wereport a method to prevent desorption and ion-exchange reaction ofmetal oxide/chalcogenide on electrode surfaces using a polyelectrolytemultilayer during sequential chemical bath deposition. By controllingthe ion permeability of the polyelectrolyte multilayer, Cu2–xSe film was successfully deposited on the CdS film.The Cu2–xSe/CdS film is confirmedby UV–vis absorption spectroscopy, scanning electron microscopy,energy dispersive X-ray analysis, and X-ray powder diffractometer.Furthermore, the Cu2–xSe/CdS filmswere investigated as photoinduced charge transfer devices which showedphotocurrents of 0.22 mA/cm2under illumination (I= 100 mW/cm2). [ABSTRACT FROM AUTHOR]

In regard to electric devices, currently designed large-scale distributed generation systems require a precise prediction strategy based on the composition of internal component owing to an environmental fluctuating condition and forecasted power variation. A number of renewable resources, such as solar or marine based energies, are made up of a low voltage direct current (DC) network. In addition to actively considering a power compensation plan, these generation systems have negative effects, which can be induced to a connected power system. When a storage is connected to a DC-based generation system on an inner network along with other generators, a precise state analysis plan should back the utilization process. This paper presents a cooperative operating condition, consisting of the shared DC section, which includes photovoltaic (PVs) and energy storage devices. An active storage management plan with voltage-expectation is introduced and compared via a commercialized electro-magnetic transient simulation tool with designed environmental conditions. Owing to their complexity, the case studies were sequentially advanced by dividing state analysis verification and storage device operation. [ABSTRACT FROM AUTHOR]

Abstract: Triruthenium carbonyl clusters {[Ru3(Br)(CO)11]− (denoted as Ru-1), [Ru3(μ 2-Br)(CO)10]− (denoted as Ru-2), and [Ru3(μ 3-NPh)(Br)(CO)9]− (denoted as Ru-3)} were synthesized on di(3-aminopropyl)viologen (DAPV)/indium tin oxide (ITO) using a surface reaction in a ruthenium (III) carbonyl [Ru3(CO)12] solution, and were applied to photoelectrochemical cells (PECs) at the molecular level. The formation of DAPV on ITO was realized in the form of self-assembled monolayers. Ru3(CO)12 then easily reacted with the Br− of DAPV, and a mixture of Ru-1 and Ru-2 was formed on DAPV/ITO. Furthermore, Ru-3 was successfully anchored on DAPV/ITO by adding nitrosobenzene in order to react with Ru-2 on DAPV/ITO. The photocurrents of (Ru-1 and Ru-2)/DAPV/ITO and Ru-3/DAPV/ITO in PECs at the molecular level were 6.3nAcm−2 and 8.6nAcm−2, respectively. The quantum yield of Ru-3/DAPV/ITO was ∼0.8%. Time-resolved photoluminescence spectroscopy and emission spectroscopy were recorded to bring out the photoinduced charge transfer process from ruthenium clusters to DAPV. [Copyright &y& Elsevier]

Abstract: Chemical functionalization of carbon nanotubes (CNTs) can strongly affect the efficiency of solar cells due to change of three factors viz. electronic energy structures, interfacial resistance, and electrical field. Therefore, it is worthwhile to investigate the influence of these three factors on the solar cells based on the functionalization of various active molecules in CNTs. In the present study, we investigate the influence of the three factors in the efficiency of superstrate-type Cu(In,Ga)Se2 (CIGS) solar cells [i.e. F-doped SnO2/CNTs/CdS/CIGS/Au] by encapsulation of electron withdrawing and donating organic molecules inside CNTs. The CIGS solar cell was characterized using the electronic diagram, electrochemical impendence spectroscopy, reverse field emission currents, and currents–voltages curves. [Copyright &y& Elsevier]