Sub-bandgap photocurrent response and carrier transport properties of undoped semi-insulating LEG GaAs as a composite

Undoped (ND) semi-insulating (SI) liquid encapsulated Czochralski (LEC) GaAscrystals were investigated by photocurrent and temperature-dependent Hall measurements. It isindicated that strong nonuniformities in the distributions of impurities and defects can occur forthe NDSILEC GaAs crystal grown under a condition with strong constitutional supercooling. In suchcase, the deep level that dominates Fermi level is spacial location dependent, and the GaAs crystalbecomes a composite consisting of a large number of elementary domains with differentconductivities. The sub-bandgap photocurrent response and the carrier transport properties for thiskind of composite are quite different from those for homogeneous NDSILEC GaAs.

Iodoplumbate(Ⅱ)-based Hybrid Templated by 1,4-Diazabicyclo[2.2.2]octane Derivative：Structure,Photocurrent Response Behavior and Photocatalytic Activity for the Degradation of Organic Dye

A new iodoplumbate/organic hybrid,[（Et_2DABCO）_2（Pb_3I_（11））（H3 O）]n（1,Et_2DABCO = N,N？-diethyl-1,4-diazabicyclo[2.2.2] octane） has been synthesized using solution method.According to X-ray diffraction structural analysis,the unique（Pb_3I_（11））_n^（5n-） chain in 1 is constructed from face-and edge-sharing PbI_6 octahedra,which is templated by（Et_2DABCO）^（2＋） dication possessing both rigidity and flexibility.C-H...I hydrogen bonds contribute to the structure extending from 1D chains to a 3D network.Its energy band gap of 2.64 eV indicates its broad-gap semiconductor nature.It exhibits both photocurrent response property and photocatalytic activity for the degradation of rhodamine B.

Ethoxycarbonylmethyl Viologen Induced Metal Halide-based Hybrids:Structures,Photoluminescence and Photocurrent Response Behavior

Two new ethoxycarbonylmethyl viologen induced metal halide-based hybrids,(Ae V)(BiI)(DMF)(1)and(Ae V)(CoCl)(2)(AeV=N,N?-bis(ethoxycarbonylmethyl)-4,4?-bipyridinium)have been synthesized and structurally determined by X-ray diffraction method.Under the direction of a new template AeV,the(BiI)tetramer constructed from four edge-sharing BiIoctahedra(for 1)and(CoCl)mono-nuclear(for 2)were obtained.Furthermore,C–H···O and C–H···X(X=I,Cl)hydrogen bonds contribute to the extension of structures from 0-D to 1-D chains.Their energy band gaps of 2.18 and 2.41 eV indicate their semiconductor properties,and the photoluminescence was detected on 1.Interestingly,2 exhibits good photocurrent response behavior.Electronic structure analysis was executed to correlate the structure/property.

Coal Based Carbon Dots for Fe^(3+) Detection and Photoelectric Catalysis

The carbon dots(CDs)could be applied in advanced field by using their sensitivity of the optical phenomenon.In this paper,the CDs in an average size of 3.75 nm was synthesized from coal by one-step solvothermal method,in which ethylenediamine was a reaction solvent and a nitrogen-containing precursor in the system.A blue-green fluorescence appeared under ultraviolet light.The strongest fluorescence emission was recorded at 480 nm under the excitation wavelength of 400 nm.The coal-based CDs could specifically recognize Fe^(3+)and the detection limit was 0.103μM.The coal-based CDs/TiO_(2) composite displayed an improved photoelectric response in 4 times comparing that of the TiO_(2) under the ultraviolet light with intensity of 10 mW cm_(-2).The photocatalytic activity over the degradation of organic molecules was accelerated as well.

Syntheses,Structures and Photocurrent Response Properties of Two Crystals Based on Tetrathiafulvalene Derivatives

In this paper,two compounds[Zn_(2)^(2+)(2,6-bis(4΄-pyridyl)-TTF)(TPA)_(2)^(2-)](1)and[Cd^(2+)(2,6(7)-bis(4΄-pyridyl)-TTF)(TPA)2-(H_(2)O)_(2)](TTF=tetrathiafulvalene,TPA=terephthalic acid)(2)were synthesized by using solvothermal method and characterized by single-crystal X-ray.The purity of the two compounds was confirmed by their PXRD data.We also tested the photocurrent responses of these two compounds,and found they could generate photocurrent signal when exposed to light,but the photocurrent intensity of compound 2 is significantly greater than that of 1.From the crystal structure analysis,the possible reason for this phenomenon is that 2 has a more compact ligand arrangement than 1,leading to a higher carrier density and easier excitation.

Haloplumbate Nanochains Templated by Quaternary Phosphorus:Good Water Stabilities,Thermochromic Luminescence and Photocurrent Responses

Two triphenylmethylphosphonium/haloplumbate hybrids,i.e.,[(PPh3Me)2(Pb2I6)∙CH3CN]n(1)and[(PPh3Me)(PbBr3)]n(2),have been prepared,in which the(PbX3)nn-nanochains built from face-sharing PbX6 octahedra are surrounded by organic templates to assemble the core-shell quantum well.Besides,C−H…πinteractions among Ph3PMe+cations can also be detected,which give rise to the 2-D organic layer of 1 and 1-D chain for 2.The good water stabilities could be induced by the strong C−H…πinteractions,which can deter the hydrolysis reaction.The energy band gaps of this work mainly derive from the charge transfer of organic components,but their luminescence stems from the inorganic(PbX3)nn-nanochains with co-existence of free excitons and self-trapped excitons.At temperature lower than 117 K,strong quantum confinement will rule out the free excitons,and self-trapped excitons will dominate,resulting in red-shift luminescence.Moreover,effective and repeatable photocurrent responses can be found in these hybrids.

Solvothermal Synthesis,Crystal Structure and Photocurrent Property of a Ti_6-Core-based Titanium Oxo Cluster

A Ti_(6)-core-based titanium oxo cluster (TOC)[Ti_(6)(m_(2)-O)_(2)(m_(3)-O)_(2)(Bpo)_(2)(PhCOO)_8(Oi Pr)_4]assembled by 2,2'-biphenol (H_(2)Bpo) and benzoic acid has been synthesized and characterized by IR,elemental analyses,thermogravimetric analysis and X-ray diffraction technique.Single-crystal X-ray diffraction analysis revealed that the complex crystallizes in monoclinic system,space group P2_(1)/n.The structure contains two Ti_(3)(m_(3)-O) units featuring a flat mode as building blocks.Solid-state UV/Vis absorption spectrum reveals that complex 1 shows a wide range from 240 to 650 nm.Moreover,the optical band gap of 1 is estimated to be 2.35 eV.Additionally,the Ti_6-TOC exhibits good photocurrent response.

Noble metal nanoclusters and their in situ calcination to nanocrystals： Precise control of their size and interface with Ti02 nanosheets and their versatile catalysis applications

In this work, we present a new versatile strategy to prepare noble metal （Au, Ag and Cu） nanoclusters on TiO2 nanosheets in large scales with exposed （001） facets with controlled size, crystalline interface, and loading amount. By precise in situ calcination, the metal （M = Au, Ag, and Cu） nanocrystals with controllable size and better crystalline interface with the TiO2 support have been prepared. The potential application of the as-prepared Au, Ag, and Cu nanoclusters on TiO2 nanosheets as potential heterogeneous catalysts for organic synthesis, such as catalytic reduction of 4-nitrophenol to 4-aminophenol, has been demonstrated. After calcination, Au, Ag, and Cu nanocrystals were found to be proficient cocatalysts for photocatalytic H2 evolution, particularly the Au cocatalyst. Based on precise high-resolution transmission electron microscopy （HRTEM） and inductively coupled plasma optical emission spectrometry （ICP-OES） analyses, the flexible control of their size and loading amount as well as their intimate contact with the TiO2 nanosheet enhanced the photocatalytic H2 evolution activity and the sensitivity of the photocurrent response of the film. Furthermore, this aqueous-directed synthesis of metal nanoclusters on a support will generate further interest in the field of nanocatalysis.

A novel 58-nuclei silver nanowheel encapsulating a subvalent Ag64+ kernel

The combination of CrO4^2-anion and N,N′-dimethylformamide(DMF)-containing solvent helps to stabilize an atom-precise ultrasmall Ag6 kernel into a 52-nuclei silver shell,giving a core-shell Ag6@Ag52 wheel-like structure(SD/Ag58b).The solution behavior and photocurrent response property were investigated in details.

In Situ Capture of a Ternary Supramolecular Cluster in a 58-Nuclei Silver Supertetrahedron

Although inorganic anion templates are highly appreciated in the synthesis of nanosized silver clusters,supramolecular clusters used as templates to mold silver nanoclusters remain as-yet-unknown due to their existence as volatile forms in solution.Here,we report the synthesis of a novel silver-thiolate nanocluster(SD/Ag58a),comprising an outer tetrahedral cage of 58 silver atoms and a central supramolecular cluster[CH_(3)OH@(SO_(4))_(4)(H_(2)O)6]8−(hereafter abbreviated as CS_(4)H_(6)).Ternary CS_(4)H_(6) cluster was constructed from an(SO_(4))_(4) tetrahedron encaging one CH_(3)OH molecule inside and six water molecules sitting between paired SO_(4)^(2−)ions to form the[SO_(4)…H_(2)O…SO_(4)]hydrogen bonds(H-bonds).Also,the CS4H6 could coordinate to the inner wall of the Ag58 cage by forming Ag-O bonds,exerting templating effect on the formation of SD/Ag58a.Moreover,SD/Ag58a showed a photocurrent response upon visible light irradiation and emitted luminescence in the near-infrared(NIR)region at a cryogenic temperature.This work exemplifies the ternary supramolecule templating effect in the construction of silver nanocluster and facilitates understanding of the structure of complex solvated anion cluster in atomic precision.

Photoconductivity and surface chemical analysis of ZnO thin films deposited by solution-processing techniques for nano and microstructure fabrication

The fabrication of zinc oxide(ZnO) from inexpensive solution-processing techniques,namely,electrochemical deposition and electrospinning were explored on various conducting and mesoporous semiconducting surfaces.Optimised conditions were derived for template- and self-assisted nano/micro structures and composites. ZnO thin films were annealed at a fixed temperature under ambient conditions and characterised using physical and optical techniques.The photocurrent response in the UV region shows a fast rise and double decay behaviour with a fast component followed by a slow oscillatory decay.Photocurrent results were correlated with surface chemical analysis from X-ray photoelectron spectroscopy.Various characterisation details reveal the importance of fabrication parameter optimisation for useful low-cost optoelectronic applications.

Halogen-bonded Cocrystal Based on Tetrathiafulvalene Derivatives

In this paper, two cocrystals 1 and 2 with the same chemical composition [L1.L2 ](L1 = bis(4’-pyridyl)-TTF, L2 = 4,4’-diiodophenyl) were synthesized by slow diffusion with different solvent systems. Cocrystals 1 and 2 were characterized by single-crystal X-ray and the purity of these two cocrystals was confirmed by PXRD data. The photocurrent responses of these two cocrystals were also tested. Only cocrystal 1 could generate photocurrent signal when exposed to light. From the crystal structure analysis, the possible reason may come from the different biphenyl conformations in L2.