Phosphorus-fluorine chemistry—XXXVI: Preparation and chemistry of thienyldifluorophosphine

2-Thienyldifluorophosphine has been prepared by chlorine-fluorine exchange in the corresponding dichlorophosphine; the difluorophosphine has been found to undergo redox disproportionation with formation of 2-thienyltetrafluorophosphorane and pentathienylcyclopentaphosphine. Upon reaction with nickel carbonyl, 2-thienyldifluorophosphine forms a tetrasubstituted derivative which may be oxidized by iodine to give tris(thienyldifluorophosphine)nickel(II)iodide. Di- and tri-substituted derivatives of molybdenum carbonyl have been obtained through displacement of the coordinated cycloolefin by the fluorophosphine in bicycloheptadienetetracarbonyl molybdenum and cycloheptatrient-tricarbonyl molybdenum. All compounds were characterized by i.r., n.m.r., and mass spectrometry. A comparison of δ_P values for thienyl-phosphorus compounds with data for the analogous phenyl-phosphorus compounds has shown a high-field shift for the thiophene derivatives in every case. A comparison of δ_F values has shown the opposite effect.     

Comparison of Eosin yellowish dye–sensitized and CdS-sensitized TiO2 nanomaterial–based solid-state solar cells

Journal of Solid State Electrochemistry - In the present work, Eosin yellowish (EY) dye–sensitized and CdS-sensitized TiO2 photoanodes prepared by doctor blade technique, for dye (DSSC)- and...     

Stability of Sn-Pb mixed organic–inorganic halide perovskite solar cells:Progress,challenges,and perspectives

The exploration of low bandgap perovskite material to approach Shockley-Queisser limit of photovoltaic device is of great significance,but it is still challenging.During the past few years,tin–lead(Sn-Pb)mixed perovskites with low bandgaps have been rapidly developed,and their single junction solar cells have reached power conversion efficiency(PCE)over 21%,which also makes them ideal candidate as low bandgap sub-cell for tandem device.Nevertheless,due to the incorporation of unstable Sn²⁺,the stability issue becomes the vital problem for the further development of Sn-Pb mixed perovskite solar cells(PSCs).In this review,we are dedicated to give a full view in current understanding on the stability issue of SnPb mixed perovskites and their PSCs.We begin with the demonstration on the origin of instability of Sn-Pb mixed perovskites,including oxidation of Sn²⁺,defects,and interfacial layer induced instability.Sequentially,the up-to-date developments on the stability improvement of Sn-Pb mixed perovskites and their PSCs is systematically reviewed,including composition engineering,additive engineering,and interfacial engineering.At last,the current challenges and future perspectives on the stability study of Sn-Pb mixed PSCs are discussed,which we hope could promote the further application of Sn-Pb mixed perovskites towards commercialization.     

Synthesis and photophysical properties of donor–acceptor system based bipyridylporphyrins for dye-sensitized solar cells

Bipyridylporphyrin derivatives possessing a porphyrin moiety as the electron donor and bipyridyl moiety as the electron–acceptor were designed and synthesized for dye-sensitized solar cells(DSSCs). The photophysical and electrochemical properties were investigated by absorption spectrometry and cyclic voltammetry. Density functional theory(DFT) was employed to study electron distribution. From the photovoltaic performance measurements, a maximum conversion efficiency(η) of 0.38% was achieved based on the bipyridylporphyrin ruthenium dye A7(J_(SC)= 1.33 mA/cm~2, V_(OC)= 0.45 V, FF = 0.64) under 1.5 irradiation(100 mW/cm~2).     

Synthesis and spectroscopic properties of ring-fused thiophene bridged push–pull dyes and their application in dye-sensitized solar cells

Bisdimethylfluorenylamino-based push–pull dyes bearing one or two benzo[c]thiophene and its precursor bicyclo[2.2.2]octadiene (BCOD) fused thiophene as π bridge have been synthesized. The effect of fused-ring on thiophene bridge for the spectroscopic and electrochemical properties of these dyes has been investigated. Dye-sensitized solar cells fabricated with these dyes show moderate photovoltaic properties.     

Controlling optical properties and electronic energy structure of I–III–VI semiconductor quantum dots for improving their photofunctions

I–III–VI multinary semiconductors, which have low toxicity, are attracting much attention as quantum dot (QD) materials for replacing conventional binary semiconductors that contain highly toxic heavy metals, Cd and Pb. Recently, the inherent design flexibility of multinary QDs has also been attracting attention, and optoelectronic property control has been demonstrated in many ways. Besides size control, the electronic and optical properties of multinary QDs can be changed by tuning the chemical composition with various methods including alloying with other semiconductors and deviation from stoichiometry. Due to significant progress in synthetic methods, the quality of such multinary QDs has been improved to a level similar to that of Cd-based binary QDs. Specifically, increased photoluminescence quantum yield and recently narrowed linewidth have led to new application fields for multinary QDs. In this review, a historical overview of the solution-phase synthesis of I–III–VI QDs is provided and the development of strategies for better control of optoelectronic properties, i.e., electronic structures, energy gap, optical absorption profiles, and photoluminescence feature, is discussed. In addition, applications of these QDs to luminescent devices and light energy conversion systems are described. The performance of prepared devices can be improved by controlling the optical properties and electronic structures of QDs by changing their size and composition. Clarification of the unique features of I–III–VI QDs in detail will be the base for further development of novel applications by utilizing the complexity of multinary QDs.     

Emerging energy chemistry in lithium–sulfur pouch cells

正On pursuing high-energy-density energy storage systems beyond the current lithium-ion battery technique, lithium–sulfur(Li–S) batteries have attracted worldwide attention due to their ultrahigh theoretical energy density up to 500 Wh kg~(-1)[1]. The unique Li–S chemistry based on the conversion reactions between solid sulfur, dissolved lithium polysulfides, and solid lithium sulfide affords thermodynamic advantages including high cathode specific capacity and low anode potential [2]. However,     

Synthesis and characterization of porphyrin-terthiophene and oligothiophene π-conjugated copolymers for polymer solar cells

Two novel conjugated polymers with alternating main chain structures of zinc porphyrin-terthiophene (P-PTT) and zinc porphyrin-oligothiophene (P-POT) were synthesized by Stille reaction. The effect of different lengths of thiophene chains on the thermal, optical, electrochemical, and photovoltaic properties of the two copolymers were investigated in detail. P-PTT exhibited higher onset decomposition temperature (392 °C) and glass-transition temperature (152 °C) than those of P-POT. The introduction of thiophene units in the meso-aryl positions of porphyrin resulted in the red shift and broader absorption spectrum compared with zinc porphyrin (P_Zn) monomer both in chloroform solutions and on thin solid films. The electrochemical properties indicated that the energy levels of the polymers were suitable for efficient charge transfer and separation at the interface between the polymer donor and PCBM acceptor. The bulk heterojunction solar cells based on P-PTT and P-POT showed power conversion efficiencies up to 0.32% and 0.18%, respectively.     

Bioinorganic chemistry of molybdenum and tungsten enzymes: A structural–functional modeling approach

Chemical approaches toward the bioinorganic chemistry of molybdenum and tungsten enzymes had been either biomimetic (structural modeling) or bioinspired (functional modeling). Among the dithiolene type of ligands, bdt (1,2-benzene dithiolate) and related aromatic molecules as model ene–dithiolene ligands were used to react with pre-designed molybdenum complexes in organic solvents. Whereas in the alternative approach mnt (maleonitrile dithiolate) is used to mimic the ligand backbone of the central atom in the active sites of these enzymes using molybdate or tungstate as the metal source in water. Structural–functional models are known for some selected enzymes, namely, sulfite oxidase, aldehyde ferredoxin oxidoreductase, tungsten formate dehydrogenase, acetylene hydratase, polysulfide reductase and dissimilatory nitrate reductase. The protocols and methodologies adopted to achieve these model systems compared with various other model systems described in this review give testimony to chemist's ability, through chemical manipulations, to achieve the model systems which may potentially serve as structural–functional mimics of natural enzyme systems.     

Iron–dinitrogen coordination chemistry: Dinitrogen activation and reactivity

Understanding the coordination of dinitrogen to iron is important for understanding biological nitrogen fixation as well as for designing synthetic systems that are capable of reducing N₂ to NH₃ under mild conditions. This review discusses recent advances in iron–dinitrogen coordination complexes and describes the factors that contribute to the degree of activation of the coordinated N₂. The reactivity of the N₂ ligand is also reviewed, with an emphasis on protonation reactions that yield ammonia and/or hydrazine. Coordination complexes containing N₂ reduction intermediates such as diazene (N₂H₂), hydrazido (N₂H₂^2?), hydrazine (N₂H₄), nitride (N^3?), imide (NH^2?), and amide (NH₂^?) are also discussed in the context of the mechanism of N₂ reduction to NH₃ mediated by iron coordination complexes.     

Electronic and photophysical properties of the bend D–T–A–T–D derivatives for small-molecule organic photovoltaic (SM-OPV) solar cells: a DFT and TD-DFT investigation

A series of D–T–A–T–D derivatives (D, electron-donating moiety; T, π-conjugated linker; A, electron-acceptor moiety) with seven electron donor moieties and various electron abilities are designed to investigate the influence of the donor on photophysical properties for small-molecule organic photovoltaic solar cells. The 4,8-dimethoxybenzodithiophene (D₁), triphenyldsramine (D₂), 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline (D₃), 9,9-dimethyl-9H-fluorene (D₄), 9-methyl-9H-carbazole (D₅), 4-methyl-4H-dithieno-pyrrole (D₆), and 4,4-dimethyl-4H-cyclopenta-dithiophene (D₇) are adopted as the electron donor moiety. The BDTC (buta-1,3-diene-1,1,4,4-tetracarbonitrile) is used for the A moiety, and the thiophene (T) is used for the π-conjugated linker. The optimized structure of D–T–A–T–D derivatives exhibits the bend molecular conformation due to the steric effect within the A moiety. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of these derivatives are dependent on the electron donating ability of D, which influences the open-circuit voltage and driving force. Reorganization energy suggests that these derivatives are good hole-transporting type materials. Projected density of state analysis demonstrates that in the HOMO, the electron density distribution is delocalized on the terminal D and T moieties, while in the LUMO, the electron density distribution is localized mainly on the A moiety. The maximum absorption peak, which has relatively high light harvesting efficiency, is due to the π to π* transition and can be tuned by the electron-donating ability and the resonance energy of the D moiety. The bend D₆–T–A–T–D₆/D₇–T–A–T–D₇ derivatives with D moiety of 4-methyl-4H-dithieno-pyrrole (D₆) and 4,4-dimethyl-4H-cyclopenta-dithiophene (D₇) are good candidates as electron donor materials for SM-OPV.     

2,1,3-Benzothiadiazole-containing donor–acceptor–acceptor dyes for dye-sensitized solar cells

A series of organic dyes with a donor–acceptor–acceptor (D–A–A) configuration, in which various diarylthienylamine donors and a cyanoacrylic acid acceptor are bridged by a low-band-gap 2,1,3-benzothiadiazole acceptor, have been synthesized, characterized, and employed as photosensitizers for dye-sensitized solar cells (DSSCs). The adoption of 2,1,3-benzothiadiazole as the bridging acceptor endowed these tailor-made dyes with superior light-harvesting capabilities in comparison to their previously reported pyrimidine-based analogs. After fine-tuning the fabrication conditions, DSSCs based on these dyes showed solar spectral responses extending to the near-IR region and achieved power conversion efficiencies (PCEs) of up to 3.16% (OHexDPTB) under simulated AM 1.5G irradiation (100 mW cm^?2).     

Photoelectrochemical studies of ionic liquid-containing solar cells sensitized with different polypyridyl–ruthenium complexes

The efficiency of dye-sensitized nanocrystalline solar cells containing ionic liquids, composed of organic sulfonium or imidazolium iodides, or a standard organic-liquid-based electrolyte was studied, while using sensitizers based on different polypyridyl–ruthenium complexes. The dyes N-719, [cis-Ru(II)(H₂dcbpy)₂(NCS)₂(TBA)₂] and Z-907, [cis-Ru(II)(H₂dcbpy)(dnbpy)(NCS)₂, Z-907 having a more hydrophobic character, as well as a bidentate β-diketonato complex, [(dcbpy)₂Ru(acetylacetonate)]Cl⁻, was studied. Solar cells sensitized with the dye N-719 were more efficient than the Z-907 cells, for all electrolytes studied. Adding a co-adsorbent, the amphiphilic hexadecylmalonic acid (HDMA), to Z-907 solar cells containing an organic-liquid electrolyte resulted in increased overall light-to-electricity conversion efficiencies, from 3.7% to 4.0%, (100 W m⁻², AM 1.5). Possibly, this is caused by an insulating hydrophobic barrier formed to suppress unwanted electron losses. By applying TiO₂ (P25) nanoparticles, assumed to support electron transfer reactions, to the organic-liquid electrolyte, the conversion efficiency was increased from 4.1% to 4.6% (100 W m⁻², AM 1.5). In 1000 W m⁻² illumination, the highest overall short-circuit current density, 9.3 mA cm⁻², was achieved with the N-719 sensitized cells, with the TiO₂ nanocomposite-containing organic-liquid-based electrolyte. For solar cells sensitized with N-719, Z-907 or the β-diketonato complex, and containing imidazolium or sulfonium iodide ionic liquids, no improvements of the overall conversion efficiency could be noticed at addition of HDMA to the dye or nanoparticles to the electrolyte.     

Phase diagram and crystal chemistry of the La–Ca–Co–O system

The phase diagram of the La–Ca–Co–O system at 885 °C in air has been determined. The system consists of two materials that have interesting thermoelectric properties, namely, the misfit layered thermoelectric oxide solid solution, (Ca,La)₃Co₄O₉, and Ca₃Co₂O₆ which consists of 1D chains of alternating CoO₆ trigonal prism and CoO₆ octahedra. The reported La₂CaO₄ and the Ca-doped (La,Ca)₂CoO_4−z phases were not found at 885 °C. As a result of the absence of these phases, the phase diagram is significantly different from that reported at 1100 °C. Small solid solution regions of (La_1−xCa_x)₂O_3−z (0 ≤ x ≤ 0.08), (Ca_1−xLa_x)₃Co₄O₉ (0 ≤ x ≤ 0.07), and (La_1−xCa_x)CoO_3−z (0 ≤ x ≤ 0.2) were established.     

Thiophene–nitroxide radical as a novel combination of sensitizer–redox mediator for dye-sensitized solar cells

We report a novel combination of organic sensitizer and redox mediator in the electrolyte for dye-sensitized solar cells (DSSCs): a thiophene dye and nitroxide radicals. Nitroxide radicals and their oxidized counterparts of oxoammonium cations show robust reversible redox reactions, thus supporting robust DSSC operations. Moreover, their redox potentials (E _1/2) and thus open-circuit voltages (V _OC) can be tuned further by attached functional groups. Optical and electrochemical characterization reveal that these new combinations exhibit enhanced V _OC and power conversion efficiencies compared to the existing iodine mediator (I⁻/I₃⁻) due to the increased V _OC. Also, the selection of the sensitizer–redox mediator turns out to be critical in the overall cell performance. Indeed, the typical ruthenium dye loses its light absorption capability when it is operated in conjunction with the nitroxide radicals.     

Synthesis and characterization of push–pull organic semiconductors with various acceptors for solution-processed small molecule organic solar cells

New efficient push–pull organic semiconductors comprising of the bis(9,9-dimethyl-9H-fluoren-2-yl)aniline (bisDMFA) donor and the various acceptors such as NO₂, DCBP, and TCF, which were linked with bithiophene or vinyl bithiophene π-conjugation bridges, were synthesized, and their photovoltaic characteristics were investigated in solution-processed small molecule organic solar cells (SMOSCs). The intramolecular charge transfers of these materials were effectively appeared in between bisDMFA donor and acceptors, depending on the electron-withdrawing strength of acceptors. The organic semiconductors having NO₂ and DCBP acceptors exhibited the most efficient photovoltaic performance, showing power conversion efficiency (PCE) of 1.98% (±0.17) and 2.01% (±0.21), respectively. When the TiO_x thin layer was treated on photoactive layer, the organic semiconductor having NO₂ showed the best PCE of 2.70% with short circuit current of 8.19 mA/cm², fill factor of 0.40, and open circuit voltage of 0.83 V in SMOSC devices.     

Bioorthogonal chemistry: Optimization and application updates during 2013–2017

Bioorthogonal chemical groups to tag naturally occurring biomolecules in their native setting is a powerful tool for studying and manipulating biological processes, whereby unique functional groups incorporated into target biomolecules can be detected in a second step by using selective partners. On the other hand, bioorthogonal cleavage reactions enables chemically controlled spatiotemporal activation of intracellular proteins and prodrugs. Considerable attention has been focused on the bioorthogonal reactions, not only optimizing the known bioorthogonal reagents to gain fast reaction kinetics, high stability of the reagents and the products, but also extending new applications as well as developing new types of bioorthogonal reactions.     

Organic dyes based on triphenylamine for dye-sensitized solar cells:Structure–property relationships

Three new organic dyes based on triphenylamine with a structure of A-D-A-D-A(D1),A-D-A(D2) and D-A(D3) were designed,theoretically calculated and synthesized for dye-sensitized solar cells.Dye D1 exhibits a broader absorption than D2 and D3,due to the intramolecular charge transfer between the donor triphenylamine and the acceptor benzothiadiazole.Dye D1 exhibits a lower HOMO and a lower LUMO than D2 and D3 due to the electron-withdrawing benzothiadiazole.The number of anchoring group cyanoacrylic acid has no obvious influence on absorption and energy levels of D2 and D3.The LUMO of D1 locates on benzothiadiazole rather than cyanoacrylic acid anchoring groups,while the LUMOs of D2 and D3 are localized on cyanoacrylic acid.D2 and D3 give higher short-circuit current density than D1.D3 with one anchoring group gives the highest open-circuit voltage.Consequently,the D3-based device gives the highest efficiency.     

Surface and Antimicrobial Properties of N-Palmitoyl Amino Acid–Based Surfactants

Synthesized sodium N-pamitoyl amino acids were evaluated for surface and antimicrobial properties and compared with sodium lauryl sulfate (SLS). Emulsion stability of the amino acid surfactants and calcium tolerance of the sodium N-palmitoyl isoleucine were better as compared to SLS. Wetting ability and foaming properties of the palmitic acid-based surfactants were inferior to SLS. N-Acyl amino acids exhibited better antibacterial activity compared to sodium salts of N-acyl amino acids and standard compounds against Staphylococcus aureus MLS-16 and Bacillus subtilis. These studies revealed that the palmitoyl amino acid surfactants can be exploited in household, skin care formulations, and industrial applications.