TiO2/BiVO4 Nanowire Heterostructure Photoanodes Based on Type II Band Alignment

Metal oxides that absorb visible light are attractive for use as photoanodes in photoelectrosynthetic cells. However, their performance is often limited by poor charge carrier transport. We show that this problem can be addressed by using separate materials for light absorption and carrier transport. Here, we report a Ta:TiO2|BiVO4 nanowire photoanode, in which BiVO4 acts as a visible light-absorber and Ta:TiO2 acts as a high surface area electron conductor. Electrochemical and spectroscopic measurements provide experimental evidence for the type II band alignment necessary for favorable electron transfer from BiVO4 to TiO2. The host–guest nanowire architecture presented here allows for simultaneously high light absorption and carrier collection efficiency, with an onset of anodic photocurrent near 0.2 V vs RHE, and a photocurrent density of 2.1 mA/cm2 at 1.23 V vs RHE

Modulation of gut microbiota and delayed immunosenescence as a result of syringaresinol consumption in middle-aged mice

Age-associated immunological dysfunction (immunosenescence) is closely linked to perturbation of the gut microbiota. Here, we investigated whether syringaresinol (SYR), a polyphenolic lignan, modulates immune aging and the gut microbiota associated with this effect in middle-aged mice. Compared with age-matched control mice, SYR treatment delayed immunosenescence by enhancing the numbers of total CD3+ T cells and naïve T cells. SYR treatment induced the expression of Bim as well as activation of FOXO3 in Foxp3+ regulatory T cells (Tregs). Furthermore, SYR treatment significantly enhanced the Firmicutes/Bacteroidetes ratio compared with that in age-matched controls by increasing beneficial bacteria, Lactobacillus and Bifidobacterium, while reducing the opportunistic pathogenic genus, Akkermansia. In addition, SYR treatment reduced the serum level of lipopolysaccharide-binding protein, an inflammatory marker, and enhanced humoral immunity against influenza vaccination to the level of young control mice. Taken together, these findings suggest that SYR may rejuvenate the immune system through modulation of gut integrity and microbiota diversity as well as composition in middle-aged mice, which may delay the immunosenescence associated with aging. © 2016 The Author(s)1761sciescopu

Electronic Structures of Nucleosides as Promising Functional Materials for Electronic Devices

The energy level alignments of nucleosides fabricated between conventional Al and indium tin oxide (ITO) electrodes by means of a vacuum electrospray deposition technique were investigated using <i>in situ</i> ultraviolet and X-ray photoelectron spectroscopy measurements. The electronic structures of four nucleosidesdeoxyguanosine, deoxyadenosine, deoxycytidine, and deoxythymidinewere determined, and their interactions with Al and ITO were analyzed. When in contact with ITO, each nucleoside showed an interface dipole that reduced the work function. On the other hand, when Al was deposited on the nucleoside layers, strong chemical interactions were observed due to electron transfer from Al to the nucleosides. Compared to their nucleobase counterparts, nucleosides commonly had lower ionization energies (IEs) and electron affinities (EAs). The origin of this difference in electronic structure was analyzed with density functional theory calculations. The sugar moieties in the nucleosides were found to induce electron-donating effects on the base moiety and led to reductions in IE and EA

TiO2/BiVO4 Nanowire Heterostructure Photoanodes Based on Type II Band Alignment.

Metal oxides that absorb visible light are attractive for use as photoanodes in photoelectrosynthetic cells. However, their performance is often limited by poor charge carrier transport. We show that this problem can be addressed by using separate materials for light absorption and carrier transport. Here, we report a Ta:TiO2|BiVO4 nanowire photoanode, in which BiVO4 acts as a visible light-absorber and Ta:TiO2 acts as a high surface area electron conductor. Electrochemical and spectroscopic measurements provide experimental evidence for the type II band alignment necessary for favorable electron transfer from BiVO4 to TiO2. The host-guest nanowire architecture presented here allows for simultaneously high light absorption and carrier collection efficiency, with an onset of anodic photocurrent near 0.2 V vs RHE, and a photocurrent density of 2.1 mA/cm(2) at 1.23 V vs RHE

Synthesis and Electroluminescence Properties of 3-(Trifluoromethyl)phenyl-Substituted 9,10-Diarylanthracene Derivatives for Blue Organic Light-Emitting Diodes

Diaryl-substituted anthracene derivatives containing 3-(trifluoromethyl)phenyl) groups, 9,10-diphenyl-2-(3-(trifluoromethyl)phenyl)anthracene (1), 9,10-di([1,1′-biphenyl]-4-yl)-2-(3-(trifluoromethyl)phenyl)anthracene (2), and 9,10-di(naphthalen-2-yl)-2-(3-(trifluoromethyl)phenyl)anthracene (3) were synthesized and characterized. The compounds 1–3 possessed high thermal stability and proper frontier-energy levels, which make them suitable as host materials for blue organic light-emitting diodes. The electroluminescent (EL) emission maximum of the three N,N-diphenylamino phenyl vinyl biphenyl (DPAVBi)-doped (8 wt %) devices for compounds 1–3 was exhibited at 488 nm (for 1) and 512 nm (for 2 and 3). Among them, the 1-based device displayed the highest device performances in terms of brightness (Lmax = 2153.5 cd·m−2), current efficiency (2.1 cd·A−1), and external quantum efficiency (0.8%), compared to the 2- and 3-based devices

Enhancement in Power Conversion Efficiency of Perovskite Solar Cells by Reduced Non-Radiative Recombination Using a Brij C10-Mixed PEDOT:PSS Hole Transport Layer

Interface properties between charge transport and perovskite light-absorbing layers have a significant impact on the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a polyelectrolyte composite that is widely used as a hole transport layer (HTL) to facilitate hole transport from a perovskite layer to an anode. However, PEDOT:PSS must be modified using a functional additive because PSCs with a pristine PEDOT:PSS HTL do not exhibit a high PCE. Herein, we demonstrate an increase in the PCE of PSCs with a polyethylene glycol hexadecyl ether (Brij C10)-mixed PEDOT:PSS HTL. Photoelectron spectroscopy results show that the Brij C10 content becomes significantly high in the HTL surface composition with an increase in the Brij C10 concentration (0&ndash;5 wt%). The enhanced PSC performance, e.g., a PCE increase from 8.05 to 11.40%, is attributed to the reduction in non-radiative recombination at the interface between PEDOT:PSS and perovskite by the insulating Brij C10. These results indicate that the suppression of interface recombination is essential for attaining a high PCE for PSCs

Impacts of Molecular Orientation on the Hole Injection Barrier Reduction: CuPc/HAT-CN/Graphene

The molecular orientation affected by the interaction between a substrate and deposited molecules plays an important role in device performance. It is known that the molecular orientation influences not only the charge transport property but also its electronic structure. Therefore, the combined study of morphology and electronic structure is of high importance for device application. As a transparent electrode, graphene has many promising advantages. However, graphene itself does not have an adequate work function for either an anode or a cathode, and thus the insertion of a charge injection layer is necessary for it to be used as an electrode. In this study, the hole injection barrier (HIB) reduction was investigated at the interface of copper phthalocyanine (CuPc)/graphene with the insertion of a hexa­aza­triphenylene hexa­carbonitrile (HAT-CN) layer between them. The insertion of the HAT-CN layer roughens the originally flat graphene surface and it weakens the π-interaction between CuPc and of graphene. This induces face-on and edge-on mixed orientations of CuPc, while CuPc on bare graphene shows merely a face-on orientation. As a result, the HIB is reduced by the contribution of edge-on CuPc having lower ionization energy (0.37 eV) along with the high work function of the HAT-CN layer (0.26 eV)

Hole Injection Enhancements of a CoPc and CoPc:NPB Mixed Layer in Organic Light-Emitting Devices

The hole injection enhancement in organic light-emitting devices with the insertion of a cobalt phthalocyanine (CoPc) hole injection layer (HIL) between the indium tin oxide (ITO) anode and the <i>N</i>,<i>N</i>′-bis­(1-naphthyl)-<i>N</i>,<i>N</i>′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) hole transport layer (HTL) was demonstrated through current density–voltage–luminance measurements, in situ photoelectron spectroscopy experiments, and theoretical calculations. The CoPc HIL significantly reduces the hole injection barrier (HIB) and thus serves as an efficient HIL like the conventional copper phthalocyanine HIL. This commonality originates from their similar configurations of the highest occupied molecular orbital (HOMO), which consists of conducting macrocycle isoindole ligands, not related to the central metal. However, as the CoPc:NPB mixed HIL is inserted, the hole injection enhancements are inferior to that of a single CoPc HIL. This is due to the electron transfer from NPB to CoPc, which pulls the HOMO level of the mixed HIL down to the deeper position. The reduced hole injection with the mixed layer implies directly that the HIB between ITO and HIL dominates device performance as the so-called ladder effect of HILs