A facile synthesis of a copper(I) thiourea sulphate complex and its application for highly efficient chalcopyrite solar cells.

The precursor compound plays a crucial role in the development of low-cost chalcogenide thin-film solar cells via a solution approach. In this work, we report on the synthesis of a new complex [Cu((NH2)2CS)3]2SO4·H2O through a simple redox reaction between inexpensive Cu(CH3COO)2·H2O and thiourea (TU) in water. Using this complex as a copper source, a stable dimethylformamide solution was made and copper indium sulfoselenide CuIn(S,Se)2 thin film solar cells with a high efficiency of 12.2% have been demonstrated.

Enhancing Performance and Stability of Perovskite Solar Cells through Surface Defect Passivation with Organic Bidentate Lewis Bases.

Organic Lewis bases [2,2'-bipyridine (BPY), 4-hydroxy-1,5-naphthyridine-3-carbonitrile (DQCN), and thenoyltrifluoroacetone (TTFA)] with bi-coordination sites of N and O were employed as perovskite surface defect passivants to address the efficiency and stability issues of perovskite solar cells (PSCs), with typical phenethylammonium iodide (PEAI) and piperazinium iodide (PI) passivants as reference. The surface properties of the perovskite films before and after passivation were characterized by Fourier-transform infrared, ultraviolet-visible, photoluminescence (PL), and time-resolved PL spectroscopy, X-ray diffraction, ultraviolet photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The characterizations reveal that BPY, DQCN, or TTFA forms coordination bonds with exposed "Pb2+", leading to a slight decrease in the highest occupied molecular orbital or lowest unoccupied molecular orbital energy level and bandgap. These passivants (especially TTFA) can passivate the perovskite surface defects to inhibit non-radiative recombination while having almost no influence on the grain size and surface morphology. Utilizing the passivated perovskite as the light absorption layer, solar cells with an inverted configuration of indium tin oxide/NiO x /passivated MAPbCl x I3-x /C60/BCP/Ag have been fabricated, and power conversion efficiencies of 19.22, 17.85, 16.49, 16.31, and 17.88% have been achieved from PEAI, PI, BPY, DQCN, and TTFA, respectively. All the device performance based on passivated perovskite is superior to that of the control (15.75%) owing to the reduced carrier recombination. The device from TTFA exhibits almost comparable efficiency to that of PEAI and PI controls, indicating that TTFA has an equal excellent passivation effect to state-of-the-art PEAI and PI. Furthermore, the devices based on BPY, DQCN, and TTFA show superior long-term stability with an efficiency loss of only 13.2, 16.7, and 12.9%, respectively, after being stored for 40 days in a ∼12% humidity, low-oxygen level environment, which is 45.4, 38.8, and 44.4% for the control, PEAI, and PI devices, respectively, primarily due to the improved hydrophobicity of the perovskite surface. Our results demonstrate that it is feasible to achieve high-efficiency and long-term-stable perovskite solar cells via selecting the appropriate molecules to passivate perovskite surface defects.

Catalyst-Free [4+2] Cycloaddition of Ynamides with 2-Halomethyl Phenols To Construct 2-Amino-4H-Chromenes and α-Halo Enamides Simultaneously.

We report the development of a facile protocol for the [4+2] cycloaddition of ynamides and 2-halomethyl phenols to afford the corresponding 2-amino-4H-chromenes and α-halo enamides under catalyst-free conditions. The reaction proceeds under mild conditions and exhibits good tolerance toward various functional groups and generates high yields. The plausible mechanism involves the formation of an active intermediate keteniminium as well as o-methylene quinone.

Quantum Yields over 80% Achieved in Luminescent Europium Complexes by Employing Diphenylphosphoryl Tridentate Ligands.

Four tridentate europium(III) complexes containing a diphenylphosphoryl group are prepared with strong bonding between the ligands and centered ion, convinced by crystal structures. Compared to their parent bidentate complexes, the tridentate complexes display improved and exceptionally high photoluminescence quantum yields (PLQYs) in powder (all over 80%, best 91%), as well as in a CH2Cl2 solution and poly(methyl methacrylate) films, benefiting from compact, stable, and saturated coordination.

Color-Stable White Organic Light-Emitting Diodes Utilizing a Blue-Emitting Electron-Transport Layer.

We have fabricated efficient and color-stable white organic light-emitting diodes (WOLEDs) based on a simple double-layer device structure consisting of a blue-emitting oligoquinoline electron-transport layer and a poly(N-vinyl carbazole) layer doped with phosphorescent green and red iridium emitters. Pure white color with the CIE coordinates from (0.30, 0.31) to (0.34, 0.37) in the whole operating bias voltage range and luminous efficiency higher than 7 cd/A at a brightness up to 12 000 cd/m2 was achieved. These results demonstrate a new strategy to realizing easily processable, highly efficient, and color-stable WOLEDs with a simple structure.

A Strategy to Simplify the Preparation Process of Perovskite Solar Cells by Co-deposition of a Hole-Conductor and a Perovskite Layer.

The feasibility of co-depositing a hole-conductor and a perovskite layer is demonstrated to simplify the preparation process of perovskite solar cells. The CuSCN incorporated in the perovskite layer can participate in forming the perovskite/CuSCN bulk-heterojunction and accelerate hole transport effectively, which eventually leads to a maximum power conversion efficiency of 18.1% with almost no J-V hysteresis.

Water-Soluble and Highly Luminescent Europium(III) Complexes with Favorable Photostability and Sensitive pH Response Behavior.

Two highly luminescent and water-soluble Eu(III) complexes, Eu1 and Eu2, based on novel carboxyl-functionalized 1,5-naphthyridine derivatives 8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L1) and 7-cyano-8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L2), respectively, are designed and synthesized. The crystal structure of Eu2 indicates that the central Eu(III) ion is nine-coordinated by three tridentate ligands (O^N^O). Both Eu1 and Eu2 show strong luminescence in aqueous solution with quantum yields (lifetimes) of 28% (1.1 ms) and 14% (0.76 ms), respectively. The chelates display unique UV-light stability in solution and remain highly emissive after 100 min of strong UV irradiation (∼300 W·m-2 at 345 nm). Moreover, they exhibit reversible luminescence intensity changes with varied pH values, and the response mechanism is investigated. "Turn-on" of the Eu(III) emission upon increasing pH is realized by ligand structure change from keto to enol anion form, resulting in red-shifted absorption band and suppressed quenching from solvents and N-H vibration upon deprotonating. The results show that these novel Eu(III) complexes are quite intriguing for potential application as bioimaging agents and pH probes.

High-performance inverted planar heterojunction perovskite solar cells based on a solution-processed CuOx hole transport layer.

During the past several years, methylammonium lead halide perovskites have been widely investigated as light absorbers for thin-film photovoltaic cells. Among the various device architectures, the inverted planar heterojunction perovskite solar cells have attracted special attention for their relatively simple fabrication and high efficiencies. Although promising efficiencies have been obtained in the inverted planar geometry based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) sulfonic acid ( PEDOT: PSS) as the hole transport material (HTM), the hydrophilicity of the PEDOT: PSS is a critical factor for long-term stability. In this paper, a CuOx hole transport layer from a facile solution-processed method was introduced into the inverted planar heterojunction perovskite solar cells. After the optimization of the devices, a champion PCE of 17.1% was obtained with an open circuit voltage (Voc) of 0.99 V, a short-circuit current (Jsc) of 23.2 mA cm(-2) and a fill factor (FF) of 74.4%. Furthermore, the unencapsulated device cooperating with the CuOx film exhibited superior performance in the stability test, compared to the device involving the PEDOT: PSS layer, indicating that CuOx could be a promising HTM for replacing PEDOT: PSS in inverted planar heterojunction perovskite solar cells.

A Hexakis Terpyridine-Fullerene Ligand in Six-Fold Ruthenium, Iridium, and Iron Complexes: Synthesis and Electrochemical Properties.

An unprecedented straightforward route to six-fold terpyridine ligands around C60 , the latter being regioselectively functionalized in pseudo-octahedral positions using a six-fold Bingel reaction, is reported. Ruthenium, iridium, and iron complexes have been synthesized, and unambiguously characterized by NMR, MS, and cyclic voltammetry.

Solution-Processed CuS NPs as an Inorganic Hole-Selective Contact Material for Inverted Planar Perovskite Solar Cells.

Organic-inorganic hybrid perovskite solar cells (PSCs) have drawn worldwide intense research in recent years. Herein, we have first applied another p-type inorganic hole-selective contact material, CuS nanoparticles (CuS NPs), in an inverted planar heterojunction (PHJ) perovskite solar cell. The CuS NP-modification of indium tin oxide (ITO) has successfully tuned the surface work function from 4.9 to 5.1 eV but not affect the surface roughness and transmittance, which can effectively reduce the interfacial carrier injection barrier and facilitate high hole extraction efficiency between the perovskite and ITO layers. After optimization, the maximum power conversion efficiency (PCE) has been over 16% with low J-V hysteresis and excellent stability. Therefore, the low-cost solution-processed and stable CuS NPs would be an alternative interfacial modification material for industrial production in perovskite solar cells.

Facile and Effective Functionalization of Graphene Oxide by Boron-Oxygen Covalent or Bingel Cyclopropanation Reaction.

Functionalized graphene oxide (GO-BPh2), was obtained via one step reaction between triphenyl boron and oxygen-containing groups on graphene sheets. In addition, functionalized graphene oxide (GO-Carbene) was obtained via bingel cyclopropanation reaction of active double bands on graphene sheets. Both functionalized materials can be homogeneously distributed into ortho-dichlorobenene. They were characterized by FTIR spectroscopy, UV Vis NIR spectroscopy, thermal gravimetric analysis, raman spectra, and X-ray photoelectron spectroscopy (XPS). FTIR, TGA and XPS results prove that phenyl boron has been successfully attached to the graphene sheets by covalent bonds. And the Raman spectra and XPS confirm that many carbon double bands changed into carbon single bands on graphene sheets after cyclopropanation reaction.

Controllable and Reversible Dispersiblity of Graphene Materials by a Generic Organometallic Functionalization.

A general and reversible functionalization method has been developed for reduced graphene oxide (rGO) based on a simple reaction sequence. In this sequence, the chemical functionalization of reduced graphene oxide (rGO) was first carried out by a nucleophilic addition of n-butyllithium (n-BuLi) to rGO sheets, followed by a subsequent coupling step of intermediates (n-Bu-rGO)n-Li(n+) with alkyl halide, leading to functionalized rGO with controllable and reversible dispersiblity in either nonpolar or polar solvents depending on the functional groups. Next, the functional groups could be reversibly removed by solvothermal treatment to generate reduced graphene sheets. Then the reduced materials could be again functionalized using the same reaction sequence above with either the same or different functional groups to almost the same extent of the first functionalization cycle.

Direct Observation of Long Electron-Hole Diffusion Distance in CH3NH3PbI3 Perovskite Thin Film.

In high performance perovskite based solar cells, CH3NH3PbI3 is the key material. We carried out a study on charge diffusion in spin-coated CH3NH3PbI3 perovskite thin film by transient fluorescent spectroscopy. A thickness-dependent fluorescent lifetime was found. By coating the film with an electron or hole transfer layer, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) or 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) respectively, we observed the charge transfer directly through the fluorescence quenching. One-dimensional diffusion model was applied to obtain long charge diffusion distances in thick films, which is ~1.7 µm for electrons and up to ~6.3 µm for holes. Short diffusion distance of few hundreds of nanometer [corrected] was also observed in thin films. This thickness dependent charge diffusion explained the formerly reported short charge diffusion distance (~100 nm) in films and resolved its confliction to thick working layer (300-500 nm) in real devices. This study presents direct support to the high performance perovskite solar cells and will benefit the devices' design.

CuSCN-Based Inverted Planar Perovskite Solar Cell with an Average PCE of 15.6%.

Although inorganic hole-transport materials usually possess high chemical stability, hole mobility, and low cost, the efficiency of most of inorganic hole conductor-based perovskite solar cells is still much lower than that of the traditional organic hole conductor-based cells. Here, we have successfully fabricated high quality CH3NH3PbI3 films on top of a CuSCN layer by utilizing a one-step fast deposition-crystallization method, which have lower surface roughness and smaller interface contact resistance between the perovskite layer and the selective contacts in comparison with the films prepared by a conventional two-step sequential deposition process. The average efficiency of the CuSCN-based inverted planar CH3NH3PbI3 solar cells has been improved to 15.6% with a highest PCE of 16.6%, which is comparable to that of the traditional organic hole conductor-based cells, and may promote wider application of the inexpensive inorganic materials in perovskite solar cells.

Synthesis of highly functionalized C60 fullerene derivatives and their applications in material and life sciences.

Highly functionalized fullerenes can be efficiently constructed by various techniques. However, the challenge is to synthesize highly symmetrical fullerenes. Recently, a number of X-ray structures have been disclosed showing the high symmetry of substituted fullerenes. By reviewing the major types of multi functionalized fullerenes through selected examples with a link to the structural assignments, the authors intend to give a concise overview to the specialist in the field and to provide the non-specialist with a tool box of possibilities.

Individualized rituximab treatment for relapsing neuromyelitis optica: a pediatric case report.

BACKGROUND: Neuromyelitis optica is an autoimmune inflammatory disorder of the central nervous system. Current therapeutic approaches are based on small uncontrolled trials, case series, or case reports. There are only a few case reports describing rituximab for pediatric neuromyelitis optica. PATIENT: A 7-year-old girl with neuromyelitis optica had high disease activity with recurrent myelitis and steroid dependence. A remarkable increase of CD19(+) B-cell count in the peripheral blood mononuclear cells and seropositivity for anti-aquaporin 4 antibody were detected at each attack. After induction therapy with rituximab, the CD19(+) B-cell number was significantly reduced and sustained at low levels. The level of serum anti-aquaporin 4 antibody normalized. She was relapse-free over 1-year follow-up period. An individualized maintenance therapy scheme is underway. CONCLUSION: Treatment with rituximab for relapsing neuromyelitis optica requires an individualized regimen to optimize the frequency and dosage of administration to maximize efficacy yet minimize overtreatment and cost. Personal levels of CD19(+) B cells in peripheral blood mononuclear cells at previous attacks and responsiveness to rituximab in induction therapy may be two useful indicators in establishing individualized maintenance therapy schemes for relapsing neuromyelitis optica.

Environmentally friendly approaches toward the production of processable graphene by exfoliation of graphite using ionic liquid.

A facile, low-cost and environmentally friendly method was developed to prepare processable graphene materials by direct exfoliation of expandable graphite flakes under wet ball milling conditions in ionic liquids. The graphene nano-sheets obtained in this method were characterized by AFM, Raman spectroscopy, UV-NIR. Thin-film field-effect transistors made from this graphene sheets exhibit ambipolar effect, an average hole mobility of -0.29 cm2 V(-1) s(-1), electron mobility of -0.57 cm2 V(-1) s(-1) was obtained.

Rapid and effective functionalization of graphene oxide by ionic liquid.

Functionalized graphene oxide (DDIB-GO) sheets, which can be homogeneously distributed into ortho-dichlorobenene, were obtained via rapid and effective covalent functionalization with imidazolium ionic liquids (1,3-didodecylimidazolium bromine) through ion exchange. The resulting DDIB-GO sheets were characterized by Fourier transform infrared spectroscopy (FTIR), UV Vis NIR spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), Atomic force microscopy (AFM). Furthermore, FTIR, XPS and TGA show that the 1,3-didodecylimidazolium have been covalently attached to the GO sheets. UV Vis NIR, TEM, and AFM demonstrate that after functionalization, the size and shape of DDIB-GO sheets had little change compared with GO sheets and it was mostly dispersed in single layer. And good electronic conductivity of the film prepared from DDIB-GO in ODCB was obtained after high temperature annealing.