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Mosconi E.,CNR Institute of Molecular Science and Technologies | Amat A.,CNR Institute of Molecular Science and Technologies | Nazeeruddin M.K.,Institute of Chemical science and Engineering | Gratzel M.,Institute of Chemical science and Engineering | De Angelis F.,CNR Institute of Molecular Science and Technologies
Journal of Physical Chemistry C | Year: 2013

We computationally investigate organometal CH3NH 3PbX3 and mixed halide CH3NH 3PbI2X perovskites (X = Cl, Br, I), which are key materials for high efficiency solid-state solar cells. CH3NH 3PbX3 perovskites exhibited the expected absorption blue shift along the I → Br → Cl series. The mixed halide systems surprisingly showed the CH3NH3PbI3 and the CH3NH3PbI2Cl (or CH3NH 3PbI3-xClx) perovskites to have similar absorption onset at ∼800 nm wavelength, whereas CH3NH 3PbI2Br absorbs light below ∼700 nm. To provide insight into the structural and electronic properties of these materials, in light of their application as solar cell active layers, we perform periodic DFT calculations on the CH3NH3PbX3 and CH 3NH3PbI2X perovskites. We find a good agreement between the calculated band structures and the experimental trend of optical band gaps. For the mixed halide perovskites our calculations show the existence of two different types of structures with different electronic properties, whose relative stability varies by varying the X group. For these systems, the calculated formation energies decrease in the order I > Br > Cl, in line with the observed miscibility of CH3NH3PbI3 and CH3NH3PbBr3 compounds, while suggesting a comparatively smaller chlorine incorporation into CH3NH 3Pb(I1-xClx)3 compounds. We also show that Cl atoms preferentially occupy the apical positions in the PbI 4X2 octahedra, while Br atoms may occupy both apical and equatorial positions, consistent with reported lattice parameters. The interplay of the organic and inorganic components of the perovskites, possibly mediated by hydrogen bonding between the ammonium groups and the halides, seems to be the key to the observed structural variability. © 2013 American Chemical Society.

Chidley C.,Institute of Chemical science and Engineering | Haruki H.,Institute of Chemical science and Engineering | Pedersen M.G.,Institute of Chemical science and Engineering | Muller E.,Institute of Chemical science and Engineering | Johnsson K.,Institute of Chemical science and Engineering
Nature Chemical Biology | Year: 2011

We introduce an approach for detection of drug-protein interactions that combines a new yeast three-hybrid screening for identification of interactions with affinity chromatography for their unambiguous validation. We applied the methodology to the profiling of clinically approved drugs, resulting in the identification of previously known and unknown drug-protein interactions. In particular, we were able to identify off-targets for erlotinib and atorvastatin, as well as an enzyme target for the anti-inflammatory drug sulfasalazine. We demonstrate that sulfasalazine and its metabolites, sulfapyridine and mesalamine, are inhibitors of the enzyme catalyzing the final step in the biosynthesis of the cofactor tetrahydrobiopterin. The interference with tetrahydrobiopterin metabolism provides an explanation for some of the beneficial and deleterious properties of sulfasalazine and furthermore suggests new and improved therapies for the drug. This work thus establishes a powerful approach for drug profiling and provides new insights in the mechanism of action of clinically approved drugs. © 2011 Nature America, Inc. All rights reserved.

Ren P.,Institute of Chemical science and Engineering | Salihu I.,Institute of Chemical science and Engineering | Scopelliti R.,Institute of Chemical science and Engineering | Hu X.,Institute of Chemical science and Engineering
Organic Letters | Year: 2012

Copper-catalyzed direct alkylation of benzoxazoles using nonactivated secondary alkyl halides has been developed. The best catalyst is a new copper(I) complex (1), and the reactions are promoted by bis[2-(N,N-dimethylamino)ethyl] ether. © 2012 American Chemical Society.

Jeon N.J.,Korea Research Institute of Chemical Technology | Lee J.,Korea Research Institute of Chemical Technology | Noh J.H.,Korea Research Institute of Chemical Technology | Nazeeruddin M.K.,Institute of Chemical science and Engineering | And 3 more authors.
Journal of the American Chemical Society | Year: 2013

A set of three N,N-di-p-methoxyphenylamine-substituted pyrene derivatives have successfully been synthesized and characterized by 1H/ 13C NMR spectroscopy, mass spectrometry, and elemental analysis. The optical and electronic structures of the pyrene derivatives were adjusted by controlling the ratio of N,N-di-p-methoxyphenylamine to pyrene, and investigated by UV/vis spectroscopy and cyclic voltammetry. The pyrene derivatives were employed as hole-transporting materials (HTMs) in fabricating mesoporous TiO2/CH3NH3PbI3/HTMs/Au solar cells. The pyrene-based derivative Py-C exhibited a short-circuit current density of 20.2 mA/cm2, an open-circuit voltage (Voc) of 0.886 V, and a fill factor of 69.4% under an illumination of 1 sun (100 mW/cm2), resulting in an overall power conversion efficiency of 12.4%. The performance is comparable to that of the well-studied spiro-OMeTAD, even though the V oc is slightly lower. Thus, this newly synthesized pyrene derivative holds promise as a HTM for highly efficient perovskite-based solar cells. © 2013 American Chemical Society.

Bunescu A.,Institute of Chemical science and Engineering | Wang Q.,Institute of Chemical science and Engineering | Zhu J.,Institute of Chemical science and Engineering
Organic Letters | Year: 2015

A copper-catalyzed oxyalkylation of allylic alcohols using nonactivated alkyl nitriles as reaction partners was developed. A sequence involving generation of an alkyl nitrile radical followed by its addition to a double bond and a copper-mediated formation of C(sp3)-O bond was proposed to account for the reaction outcome. The protocol provided an efficient route to functionalized tri- and tetrasubstituted epoxides via formation of a C(sp3)-C(sp3) and a C(sp3)-O bond with moderate to excellent diastereoselectivity. © 2015 American Chemical Society.

Marchioro A.,Institute of Chemical science and Engineering | Teuscher J.,Institute of Chemical science and Engineering | Friedrich D.,Helmholtz Center Berlin | Kunst M.,Helmholtz Center Berlin | And 4 more authors.
Nature Photonics | Year: 2014

Lead halide perovskites have recently been used as light absorbers in hybrid organic-inorganic solid-state solar cells, with efficiencies as high as 15% and open-circuit voltages of 1 V. However, a detailed explanation of the mechanisms of operation within this photovoltaic system is still lacking. Here, we investigate the photoinduced charge transfer processes at the surface of the perovskite using time-resolved techniques. Transient laser spectroscopy and microwave photoconductivity measurements were applied to TiO 2 and Al 2 O 3 mesoporous films impregnated with CH 3 NH 3 PbI 3 perovskite and the organic hole-transporting material spiro-OMeTAD. We show that primary charge separation occurs at both junctions, with TiO 2 and the hole-transporting material, simultaneously, with ultrafast electron and hole injection taking place from the photoexcited perovskite over similar timescales. Charge recombination is shown to be significantly slower on TiO 2 than on Al 2 O 3 films. © 2014 Macmillan Publishers Limited.

Oh Y.,Institute of Chemical science and Engineering | Hu X.,Institute of Chemical science and Engineering
Chemical Society Reviews | Year: 2013

Reduction of CO2 by electrochemical and photoelectrochemical methods to produce carbon-rich fuels is a heavily pursued research theme. Most of the current efforts are focused on the development of transition-metal-based catalysts. In this tutorial review, we present an overview of the development of organic molecules as mediators and catalysts for CO2 reduction. Four classes of organic molecules are discussed: tetraalkylammonium salts, aromatic esters and nitriles, ionic liquids, and pyridinium derivatives. It is shown that reactions mediated or catalyzed by these organic molecules can be competitive compared to their metal-catalyzed counterparts, both in terms of product selectivity and energy efficiency. © 2013 The Royal Society of Chemistry.

Vechorkin O.,Institute of Chemical science and Engineering | Proust V.,Institute of Chemical science and Engineering | Hu X.,Institute of Chemical science and Engineering
Angewandte Chemie - International Edition | Year: 2010

(Figure Presented) Too selective: A general and straightforward protocol for the cross-coupling of non-activated alkyl halides with heterocyclic C-H bonds has been developed. The transformation is chemo- and regioselective and many functional groups on both coupling partners are tolerated. The method employs cheap nickel/copper catalysts, and expands significantly the scope of C-H functionalization (see scheme). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Bunescu A.,Institute of Chemical science and Engineering | Wang Q.,Institute of Chemical science and Engineering | Zhu J.,Institute of Chemical science and Engineering
Organic Letters | Year: 2014

A reaction of 2-acyl substituted tetrahydroquinolines, prepared by Lewis acid-catalyzed three-component reaction of α-oxo aldehydes, anilines, and dienophiles, with in situ generated arynes afforded 5,6-dihydroindolo[1,2-a] quinolines in good to excellent yields. © 2014 American Chemical Society.

Im J.-H.,Sungkyunkwan University | Jang I.-H.,Sungkyunkwan University | Pellet N.,Institute of Chemical science and Engineering | Pellet N.,Max Planck Institute for Solid State Research | And 2 more authors.
Nature Nanotechnology | Year: 2014

Perovskite solar cells with submicrometre-thick CH3 NH3 PbI3 or CH3 NH 3 PbI 3- x Cl x active layers show a power conversion efficiency as high as 15%. However, compared to the best-performing device, the average efficiency was as low as 12%, with a large standard deviation (s.d.). Here, we report perovskite solar cells with an average efficiency exceeding 16% and best efficiency of 17%. This was enabled by the growth of CH3 NH3 PbI3 cuboids with a controlled size via a two-step spin-coating procedure. Spin-coating of a solution of CH 3 NH 3 I with different concentrations follows the spin-coating of PbI 2, and the cuboid size of CH3 NH3 PbI3 is found to strongly depend on the concentration of CH3 NH3 I. Light-harvesting efficiency and charge-carrier extraction are significantly affected by the cuboid size. Under simulated one-sun illumination, average efficiencies of 16.4% (s.d.±0.35), 16.3% (s.d.±0.44) and 13.5% (s.d.±0.34) are obtained from solutions of CH3 NH3 I with concentrations of 0.038M, 0.050 M and 0.063 M, respectively. By controlling the size of the cuboids of CH3 NH3 PbI3 during their growth, we achieved the best efficiency of 17.01% with a photocurrent density of 21.64mA-2, open-circuit photovoltage of 1.056V and fill factor of 0.741. © 2014 Macmillan Publishers Limited. All rights reserved.

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