Fluorescence Decay Lifetime of Ultrafine CdS and ZnS Particles

The fluorescence decay properties of CdS and ZnS ultrafine particles have been investigated by a single photon counting technique.We have found that the decay is dependent on the particle size,emission wavelength and colloidal sandwich structure.Shorter emission lifetimes were observed for smaller CdS particles and at shorter emission wavelength.The average emission lifetime of ZnS part in the sandwich structure of ZnS and CdS particles clearly decreased.

Photoelectrochemical Behavior of the GaAs/A1_(x)Ga_(l-x)As Superlattice Elect rode/Electrolyte Interface

Single and multiple quantum wells of lattice-matched superlattices material GaAs/A1xGal-xAs have been studied as photoelectrodes in photoelectrochemical cells containing nonaqueous electrolyte.Structured photocurrent spectra in the potential range of-1.8 to 1.0 V(vs standard calomel electrode)were obtained.The quantum yields for both superlattice electrodes were estimated and compared.

Synthesis of TiO_(2) nanotubes film and its light scattering property

TiO2 nanotubes with diameters of 10 nm and lengths up to 600 nm were fabricated by directly using com-mercial TiO2 powders P25 as the precursors via sonica-tion-hydrothermal combination approach. TiO2 nanotubes were characterized by means of X-ray powder diffractometer (XRD), scanning electron microscope (SEM), selected area electron diffraction pattern (SAED) and transmission elec-tron microscope (TEM). The light scattering property of film electrodes modified with TiO2 nanotubes was studied and revealed that TiO2 nanotubes can be used as the light scat-tering centers to increase the light absorption in dye- sensi-tized solar cells. The TiO2 nanotubes film electrodes mixed with 10% small nanoparticles TiO2 had both strong light scattering property and fine mechanical characteristics, and this kind of electrodes can be used as electrodes in improving the conversion efficiencies of dye-sensitized solar cells.

Nanocrystalline TiO_(2) thin film electrodes prepared by common pressure hydrothermal method at low temperature

Nanocrystalline TiO2 thin film electrodes have been prepared from mixed pastes of tetrabutyl titanate and nanocrystalline TiO2 particles by common pressure hydro- thermal method at low temperature. The tetrabutyl titanate was hydrolyzed and crystallized into anatase TiO2 to inter- connect nanocrystalline TiO2 particles and adhere them to conductive substrates, obtaining highly porous and me- chanically stable TiO2 nanocrystalline film. The conversion efficiencies of the dye-sensitized solar cells based on prepared electrodes on conductive glass substrates and flexible sub- strates were 4.8% and 1.9% under illumination of 100 mW/cm2, respectively.

A new type quasi-solid state electrolyte for dye-sensitized solar cells

A new type quasi-solid state electrolyte was prepared by solidifying liquid electrolytes con- taining organic solvents (such as mixture of ethylene carbonate (EC) and propylene carbonate (PC), 3- methoxypropinitrile (NMP) and N-methyl-oxazolidin- one (NMO)) with comb-like molten salt type polymer, and was for the first time employed in dyesensitized solar cells (DSSCs). The optimal electrolyte compo- sition was obtained by regulating the polymer content in the electrolytes and optimizing performance data of the electrolytes and assembled cells, yielding a maximum conversion efficiency of 6.58% (AM 1.5, 100 mW·cm?2). Furthermore, the existence of this new type polymer in the electrolyte suppresses the evaporation of organic solvent and improves the sta- bility of the cells.

Preparation of porous nanocrystalline TiO_2 electrode by screen-printing technique

Different paste has been used for preparing porous TiO2 thin film by screen-printing technique, the main component of it comes from commercial TiO2 P25 power. The dye-sensitized solar cell based on this TiO2 thin film without further chemical treatments exhibits high overall conversion efficiency of 5.81%―6.70%, even with low TiO2 content and thin film thickness. The experimental repeatability is nice and the properties of the films are uniform.

Photoelectrical performance of nanocrystalline TiO_2 film electrode sensitized by Ru(Ⅱ)-bipyridine complexes

Two kinds of Ru(Ⅱ)-bipyridine complexes, cis-di(thiocyanate)bis(2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium(Ⅱ) and cis-di(thiocyanate)bis(2,2′-bipyridyl-3,3′-dicarboxylate) ruthenium(Ⅱ), were utilized as the sensitizers to the nanocrystalline TiO-2 film electrodes. Study shows that the two dyes have quite different sensitization properties due to the strong steric effect of carboxyl groups. In addition, the pretreatment to nanocrystalline TiO-2 film electrodes with TiCl-4 was investigated, which is an effective way to improve the photoelectric conversion performances of sensitized TiO-2 electrodes.

Fluorescence and sensitization performance of phenylene-vinylene-substituted polythiophene

A new kind of polythiophene derivative, Poly(3-{2-[4-(2-ethylhexyloxy)-phenyl]-vinyl}-2,2′-bithiophene) (PTh), was applied in dye-sensitized solar cell to extend the light response of nanocrystalline TiO2 electrode. UV-vis absorption and fluorescence spectra were employed to investigate the interaction of PTh with nanocrystalline TiO2. The absorption coefficient of the PTh was high in visible part of spec- trum, and the fluorescence emission of the PTh can be efficiently quenched by TiO2 nanoparticles ow- ing to charge injection from the excited singlet state of PTh to the conduction band of the TiO2 particles. Cyclic voltammetry measurements were performed to study the dye regeneration reaction at the na- nocrystalline TiO2/electrolyte interface. The solar cell sensitized with PTh exhibited a short-circuit photocurrent (Isc) of 3.08 mA/cm2, an open circuit voltage (Voc) of 511 mV and an overall efficiency of 0.9% under the illumination of 100 mW/cm2 (AM 1.5).