Firmly attached: The short‐circuit photocurrent density and conversion yields of solar cells based on pyridine‐containing donor–acceptor π‐conjugated (D‐π‐A) dyes (see scheme) are greater than those for conventional D‐π‐A dye sensitizers that bear a carboxy group as the electron‐withdrawing anchoring group. The dyes are attached to the surface by coordinate bonding with the Lewis acid sites of TiO2.

A new-type of donor-acceptor π-conjugated (D-π-A) fluorescent dyes NI3-NI8 with a pyridine ring as electron-withdrawing-injecting anchoring group have been developed and their photovoltaic performances in dye-sensitized solar cells (DSSCs) are investigated. The short-circuit photocurrent densities and solar energy-to-electricity conversion yields of DSSCs based on NI3-NI8 are greater than those for the conventional D-π-A dye sensitizers NI1 and NI2 with a carboxyl group as the electron-withdrawing anchoring group. The IR spectra of NI3-NI8 adsorbed on TiO(2) indicate the formation of coordinate bonds between the pyridine ring of dyes NI3-NI8 and the Lewis acid sites (exposed Ti(n+) cations) of the TiO(2) surface. This work demonstrates that the pyridine rings of D-π-A dye sensitizers that form a coordinate bond with the Lewis acid site of a TiO(2) surface are promising candidates as not only electron-withdrawing anchoring group but also electron-injecting group, rather than the carboxyl groups of the conventional D-π-A dye sensitizers that form an ester linkage with the Brønsted acid sites of the TiO(2) surface.

Anthracene-boronic acid ester as a new class of fluorescence PET sensors for detection of a trace amount of water in organic solvents has been designed and developed.

A new class of fluorescence sensor for detection of water in organic solvents based on photo-induced electron transfer (PET) of anthracene coupled with an amino acid has been designed and developed.

A series of benzofuro [2,3-c]oxazolo [4,5-a]carbazole-type fluorescent dyes OH1, OH2, OH4, OH7, and OH17 with carboxyl groups on different positions of a chromophore skeleton are synthesized and applied to dye-sensitized solar cells (DSSCs) as a new class of donor-p-acceptor (D-p-A) photosensitizers. In the dye OH1, a carboxyl group acts as not only the anchoring group for attachment on TiO 2 surface but also the electron acceptor. For OH2, OH4, and OH7, on the other hand, a carboxyl group is an anchoring group, but the electron acceptor is not a carboxyl group but a cyano group. The dye OH17 has two carboxyl groups, which are located at the same positions as those of OH1 and OH7. The absorption and fluorescence spectra and cyclic voltammograms of these fluorescent dyes resemble very well, showing a negligible influence of the position of carboxyl group on photophysical and electrochemical properties of these dyes. When these dyes are used in DSSCs, however, their photovoltaic performances differ considerably. In order to elucidate the difference in the DSSC performance among the five dyes, kinetics of the electron injection from the conduction band of TiO 2 to dye cation and to I 3 À ions in solution were studied by employing the transient absorption spectroscopy and the transient photovoltage technique, respectively. It is found that the charge recombination rate for OH2 is similar to that of OH1 and is much slower than those of OH4 and OH17, consistent with the high short-circuit photocurrent densities for OH1 and OH2. On the basis of the MO calculations (AM1 and INDO/S) and the charge recombination kinetics, the differences of the photovoltaic performances among the five dyes are discussed from the viewpoint of configuration of the dyes adsorbed on TiO 2 surface, and a new molecular design for D-p-A dye sensitizers based on a control of molecular orientation and arrangement of dye adsorbed on TiO 2 surface is proposed.

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Gut befestigt: Die Photostromdichte und der Wirkungsgrad von Solarzellen auf der Basis Pyridin‐haltiger, π‐konjugierter Donor‐Akzeptor(D‐π‐A)‐Farbstoffe (siehe Schema) übertreffen die Parameter herkömmlicher D‐π‐A‐Farbstoffsensibilisatoren mit Carboxygruppen als elektronenziehender Ankergruppe. Die Farbstoffe sind über eine koordinative Bindung zu den Lewis‐sauren Zentren von TiO2 an der Oberfläche befestigt.

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