An alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor with high crystallinity exhibiting single junction solar cell efficiencies greater than 13% with low voltage losses

A new synthetic route, to prepare an alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor (C8-ITIC), is reported. Compared to the reported ITIC with phenylalkyl side chains, the new acceptor C8-ITIC exhibits a reduction in the optical band gap, higher absorptivity, and an increased propensity to crystallize. Accordingly, blends with the donor polymer PBDB-T exhibit a power conversion efficiency (PCE) up to 12.4%. Further improvements in efficiency are found upon backbone fluorination of the donor polymer to afford the novel material PFBDB-T. The resulting blend with C8-ITIC shows an impressive PCE up to 13.2% as a result of the higher open-circuit voltage. Electroluminescence studies demonstrate that backbone fluorination reduces the energy loss of the blends, with PFBDB-T/C8-ITIC-based cells exhibiting a small energy loss of 0.6 eV combined with a high JSCof 19.6 mA cm-2

Wafer-scale two-dimensional semiconductors from printed oxide skin of liquid metals

© The Author(s) 2017. A variety of deposition methods for two-dimensional crystals have been demonstrated; however, their wafer-scale deposition remains a challenge. Here we introduce a technique for depositing and patterning of wafer-scale two-dimensional metal chalcogenide compounds by transforming the native interfacial metal oxide layer of low melting point metal precursors (group III and IV) in liquid form. In an oxygen-containing atmosphere, these metals establish an atomically thin oxide layer in a self-limiting reaction. The layer increases the wettability of the liquid metal placed on oxygen-terminated substrates, leaving the thin oxide layer behind. In the case of liquid gallium, the oxide skin attaches exclusively to a substrate and is then sulfurized via a relatively low temperature process. By controlling the surface chemistry of the substrate, we produce large area two-dimensional semiconducting GaS of unit cell thickness (∼1.5 nm). The presented deposition and patterning method offers great commercial potential for wafer-scale processes

Corrigendum: Wafer-scale two-dimensional semiconductors from printed oxide skin of liquid metals.

Nature Communications 8: Article number: 14482; published: 17 February 2017; Updated: 22 March 2017 The original version of this Article contained a typographical error in the spelling of the author Omid Kavehei, which was incorrectly given as Omid Kevehei. This has now been corrected in both the PDF and HTML versions of the Article.</jats:p

Topological insights in polynuclear Ni/Na coordination clusters derived from a schiff base ligand

This article presents the syntheses, crystal structures, topological features and magnetic properties of two NiII/NaI coordination clusters (CCs) formulated [NiII3Na(L1)3(HL1 (MeOH)2] (1) and [NiII6Na(L1)5(CO3)(MeO (MeOH)3(H2O)3]·4(MeOH) 2(H2O) [2 4(MeOH) 2(H2O)] where H2L1 is the semi rigid Schiff base ligand (E)-2-(2-hydroxy-3 methoxybenzylideneamino)-phenol). Compound 1 possesses a rare NiII3NaI cubane (3M4-1) topology and compound 2 is the first example in polynuclear Ni/Na chemistry that exhibits a 2,3,4M7-1 topology

In situ formation of reactive sulfide precursors in the one-pot, multigram synthesis of Cu2ZnSnS4 nanocrystals

Herein we outline a general one-pot method to produce large quantities of compositionally tunable, kesterite Cu2ZnSnS4 (CZTS) nanocrystals (NCs) through the decomposition of in situ generated metal sulfide precursors. This method uses air stable precursors and should be applicable to the synthesis of a range of metal sulfides. We examine the formation of the ligands, precursors, and particles in turn. Direct reaction of CS2 with the aliphatic primary amines and thiols that already constitute the reaction mixture is used to produce ligands in situ. Through the use of 1H and 13C nuclear magnetic resonance, Fourier transform infrared spectroscopy, and optical absorption spectroscopy, we elucidate the formation of the resulting oleyldithiocarbamate and dodecyltrithiocarbonate ligands. The decomposition of their corresponding metal complexes at temperatures of ∼100 °C yields nuclei with a size of 1–2 nm, with further growth facilitated by the decomposition of dodecanethiol. In this way the nucleation and growth stages of the reaction are decoupled, allowing for the generation of NCs at high concentrations. Using in situ X-ray diffraction, we monitor the evolution of our reactions, thus enabling a real-time glimpse into the formation of Cu2ZnSnS4 NCs. For completeness, the surface chemistry and the electronic structure of the resulting CZTS NCs are studied. © 2013, American Chemical Society

Non-injection synthesis of Cu2ZnSnS4 nanocrystals using a binary precursor and ligand approach

We present a non-injection, one-pot synthesis of kesterite Cu2ZnSnS4 (CZTS) nanocrystals (NCs) that allows for multi-gram yields with precise control of the NCs’ metal composition. This is enabled through the selective use of a binary sulfur precursor and ligand reaction mixture, which acts to decouple the nucleation and growth stages. © 2013, The Royal Society of Chemistry

Self-Assembly of Plasmonic Near-Perfect Absorbers of Light: The Effect of Particle Size

Structures capable of perfect light absorption promise technological advancements in varied applications, including sensing, optoelectronics, and photocatalysis. While it is possible to realize such structures by placing a monolayer of metal nanostructures above a reflecting surface, there remains limited studies on what effect particle size plays on their capacity to absorb light. Here, we fabricate near-perfect absorbers using colloidal Au nanoparticles, via their electrostatic self-assembly on a TiO2 film supported by a gold mirror. This method enables the control of interparticle spacing, thus minimizing reflection to achieve optimal absorption. Slightly altering the nanoparticle size in these structures reveals significant changes in the spectral separation of hybrid optical modes. We rationalize this observation by interpreting data with a coupled-mode theory that provides a thorough basis for creating functional absorbers using complex colloids and outlines the key considerations for achieving a broadened spectral response

Hot-Carrier Organic Synthesis via the Near-Perfect Absorption of Light

Photocatalysis enables the synthesis of valuable organic compounds by exploiting photons as a chemical reagent. Although light absorption is an intrinsic step, existing approaches rely on poorly absorbing catalysts that require high illumination intensities to afford enhanced efficiencies. Here, we demonstrate that a plasmonic metamaterial capable of near-perfect light absorption (94%) readily catalyzes a model organic reaction with a 29-fold enhancement in conversion relative to controls. The oxidation of benzylamine proceeds via a reactive iminium intermediate with high selectivity at ambient temperature and pressure, using only low-intensity visible irradiation. Control experiments demonstrated that only hot charge carriers produced following photoexcitation facilitate the formation of superoxide radicals, which, in turn, leads to iminium formation. Modeling shows that hot holes with energies that overlap with the highest-occupied molecular orbital (HOMO) of the reactant can participate and initiate the photocatalytic conversion. These results have important implications for hot-carrier photocatalysis and plasmon-hot-carrier extraction

Plasmene Metasurface Absorbers: Electromagnetic Hot Spots and Hot Carriers

Light-matter interactions are extremely important, as they sustain life on Earth and can be tailored for diverse applications in areas such as solar energy conversion, chemical sensing, and information storage. One key process of these interactions is the absorption of photons. We demonstrate a novel material capable of absorbing up to 98% of incident visible light. The material comprises a thin sheet of a tightly packed two-dimensional lattice of metal nanoparticles, called plasmene, supported by a thin (subwavelength) dielectric film deposited on top of a mirror. We demonstrate how the resulting metasurface absorbers are useful in surface-enhanced spectroscopy and in the generation of plasmonic hot carriers. These structures hold great promise for applications in structural color, sensing, and photocatalysis