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A study confirms the advantage of high extinction coefficient sensitizers in realizing efficient thin film solar cells. Two novel heretoteptic synthesizers coded as K-19 and K-73 are synthesized and characterized by (super 1)H NMR, FTIR, UV-vis absorption and emission spectroscopy and excited-state lifetime and spectroelectrochemical measurements.

A new amphiphilic polypyridyl ruthenium sensitizer with two phosphonic acid anchoring groups was synthesized and used for dye-sensitized solar cells with a total power conversion efficiency of greater than or equal to 8.0 percent under simulated air mass 1.5 sunlight. The new synthesizer had excellent light soaking stabilities at moderate temperature stress in the presence of both 3-methyloxypropionitrile based and solvent-free ionic liquid electrolytes.

A thin-layer electrochemical cell is used to study the redox potential of sensitizers that are anchored on a mesophorous film, in conjunction with square-wave voltammetry. An efficiency of 6.6 percent is obtained for the first time in dye-sensitized nanocrsytalline solar cells with pure ionic liquid electrolytes, at an illumination of air mass (AM 1.5) sunlight.

Investigations on the ultrafast electron injection mechanism from the dye alizarin to wide band gap semiconductor colloids aqueous medium are presented, combined with detailed studies on population, depopulation and relaxation phenomena in trap states and their influence on the injection process. The measurements underline the crucial role of trap states in the injection mechanism of electrons from dye molecules to semiconductor surfaces.

Research is presented demonstrating the control of conduction band energies by the specific adsorption of cations on nanocrystalline particles of TiO2. Flash photolysis in propylene carbonate is used to measure the kinetics of the oxidation of iodide.

The preparation of mesoporous films of nanometer-sized particulate SrTiO3 is demonstrated and the photovoltaic behavior of dye-sensitized solar cells prepared with these films is compared with that of TiO2-based cells.

Some of the views of Frank Willig, et al, regarding the ultrafast electron transfer from photoexcited ruthenium(II) cis-di(isothiocyanato)bis(4,4'-dicarboxy-2,2'-bipyridyl), (N3), into titania, are flawed. Experimental verifications were carried out to confirm the end results of the study. The findings suggested that the results of the authors' study may have been affected by samples of degraded sensitizer. In addition, similarities in the spectra determined with degraded samples and those utilized by Willig et al may have been obtained from a degraded form of the original sensitizer.

A combined experimental and theoretical study on cationic Ir(III) complexes for organic light-emitting diodes (OLED) applications and a strategy to tune the phosphorescence wavelength and to enhance the emission quantum yields for this class of compounds is described. The results have shown that functionalization of the bpy ligand by electron-donating substituents has achieved the objective of shifting the emission energy toward the blue-region of the spectrum, reducing, at the same time, the nonradiative decay pathways.

The electronic and ionic processes in dye-sensitized solar cells (DSC) were examined with the help of electrochemical impedance spectroscopy (EIS). The decline in the lifetime of the conduction band electron in the TiO2 film led to variations in DSC performance under prolonged thermal aging.

A report on a binary ionic liquid electrolyte composed of 1-propyl-3-methylimidazolium iodide and 1-ethyl-3-methylimidazolium tricyanomethanide that reaches an unprecedented 7.4% power conversion efficiency under full air mass (AM) 1.5 sunlight, is presented. Ultramicroelectrode voltammetric, nanosecond laser transient absorbance, and photovoltaic measurements show that a high iodide concentration is required for dye regeneration to compete efficiently with charge recombination.

The ionic liquids based on the SeCN(super -)/(SeCN)(sub 3)(super -) redox couple can be employed as mediators for high-efficiency dye-sensitized solar cells. An alternative redox couple are identified that can rival and even exceed the performance of the iodide/triiodide couple even at full sunlight.

The eosin/colloidal TiO2 system lent itself to a detailed investigation of the effects of surface interaction upon the dynamics of photoinduced electron transfer from dye excited states into the conduction band of semiconductors. Vibrational relaxation of eosin singlet excited state was found from stimulated emission experiments to occur within the same time frame, precluding their complete thermalization prior to the reaction.

Electron transfer from organic dye molecules to semiconductor-colloidal systems is among the fastest reported charge-separation reactions. Investigations on alizarin complexing the surface of TiO2 semiconductor colloids in solution is presented.

The influence of applied electrical potential and the presence of potential determining ions in the electrolyte upon the kinetics of electron injection in RuL2(NCS)(sub 2)- sensitized nanocrystalline TiO2 films are studied. The result indicates that the retardation of the injection kinetics in the absence of potential determining ions is attributed to the influence of these ions upon the electronic density of states of the TiO2 electrode.

A study is conducted to show that the slow component of electron injection arises from sensitizer molecules that are loosely attached onto the surface or are present in an aggregated form. A monophasic electron transfer (ET) with a rise time shorter than 20 fs is observed when the formation of aggregates is prevented and the sensitizer is adsorbed as a monolayer on the surface of TiO2 nanocrystals.

Research was conducted to examine charge separation in solid-state dye-sensitized heterojunction solar cells. Photoinduced, interfacial charge separation across a dye-sensitized solid-state heterojunction was directly observed by means of picosecond transient absorption laser spectroscopy. Results demonstrate that it was possible to directly observe hole transfer from a photooxidized dye to a solid organic charge transport material, resulting in regeneration of the dye ground state.

Issues concerning the optical excitation in dye-sensitized nanocrystalline titanium dioxide films which results in the semiconductor being injected by an electron are presented.

A study was conducted which aimed to further advance the understanding of light-induced charge separation in natural or artificial molecular systems and of designing such systems able to efficiently convert light into chemical or electrical energy. Intramolecular and interfacial electron transfer was used to accomplish photoinduced charge separated states reaching half-life times of 300 microns. Results of the study are discussed.