Silicon-silicon π single bond.

A carbon-carbon double bond consists of a σ bond and a π bond. Recently, the concept of a π single bond, where a π bond is not accompanied by a σ bond, has been proposed in diradicals containing carbon and heteroatom radical centers. Here we report a closed-shell compound having a silicon-silicon π single bond. 1,2,2,3,4,4-Hexa-tert-butylbicyclo[1.1.0]tetrasilane has a silicon-silicon π single bond between the bridgehead silicon atoms. The X-ray crystallographic analysis shows that the silicon-silicon π single bond (2.853(1) Å) is far longer than the longest silicon-silicon bond so far reported. In spite of this unusually long bond length, the electrons of the 3p orbitals are paired, which is confirmed by measurement of electron paramagnetic resonance, and magnetic susceptibility and natural bond orbital analysis. The properties of the silicon-silicon π single bond are studied by UV/Vis and 29Si NMR spectroscopy, and theoretical calculations.

Fabrication of a high-performance dye-sensitized solar cell with 12.8% conversion efficiency using organic silyl-anchor dyes.

The co-sensitization of organic silyl-anchor dyes in dye-sensitized solar cells (DSSCs) using carbazole and coumarin dyes with organosilicon tethers for binding to titanium dioxide has been examined. We have succeeded in fabricating a high-performance DSSC with a light-to-electric energy conversion efficiency of 12.8% under one sun simulated solar irradiation.

An achievement of over 12 percent efficiency in an organic dye-sensitized solar cell.

Dye-sensitized solar cells fabricated by using a novel metal-free alkoxysilyl carbazole as a sensitizing dye and a Co(3+/2+)-complex redox electrolyte exhibited light-to-electric energy conversion efficiencies of over 12% with open-circuit photovoltages higher than 1 V by applying a hierarchical multi-capping treatment to the photoanode.

Fabrication of a dye-sensitized solar cell containing a Mg-doped TiO2 electrode and a Br3(-)/Br- redox mediator with a high open-circuit photovoltage of 1.21 V.

A dye-sensitized solar cell (DSSC) fabricated by using a Mg(2+)-doped anatase-TiO(2) electrode with an alkoxysilyl dye and a Br(3)(-)/Br(-) electrolyte solution exhibited successfully a remarkably high open-circuit photovoltage over 1.2 V, demonstrating a new possibility of DSSCs as practical photovoltaic devices.

High-pressure synthesis and correlation between structure, magnetic, and dielectric properties in LiNbO(3)-type MnMO3 (M=Ti, Sn).

LiNbO(3)-type MnMO(3) (M = Ti, Sn) were synthesized under high pressure and temperature; their structures and magnetic, dielectric, and thermal properties were investigated; and their relationships were discussed. Optical second harmonic generation and synchrotron powder X-ray diffraction measurements revealed that both of the compounds possess a polar LiNbO(3)-type structure at room temperature. Weak ferromagnetism due to canted antiferromagnetic interaction was observed at 25 and 50 K for MnTiO(3) and MnSnO(3), respectively. Anomalies in the dielectric permittivity were observed at the weak ferromagnetic transition temperature for both the compounds, indicating the correlation between magnetic and dielectric properties. These results indicate that LiNbO(3)-type compounds with magnetic cations are new candidates for multiferroic materials.