Dye-Sensitized Solar Cells Based on D-π-A Fluorescent Dyes with Pyridine Ring Forming Strong Interaction with Nanocrystalline TiO2

New-type donor-acceptor pi-conjugated (D-pi-A) fluorescent dyes OH11, OH14, and OH15 with pyridine, 4-phenylpyridine, and quinoline rings, respectively, as electron-accepting groups have been developed and their photovoltaic performance as dye-sensitized solar cells (DSSCs) are investigated. The short-circuit photocurrent densities (J(sc)) of DSSCs using OH11, OH14, and OH15 are 4.88, 3.91, and 1.72 mA cm(-2), and the solar energy-to-electricity conversion yields (eta) are 1.62, 1.30, and 0.56%, respectively, under a simulated solar light (AM 1.5, 100 mW cm-2). The IR spectra of OH11 and 0H14 adsorbed on TiO2 indicate the formation of hydrogen bonding between the pyridine ring of dyes and the hydroxy group of TiO2 surface and the formation of strong coordinate bonding between the pyridine ring of dyes and the Lewis acid site of TiO2 surface. On the other hand, in the IR spectra of OH15 adsorbed on TiO2, only the formation of weak hydrogen bonding was observed. This work suggests that the pyridine rings forming a strong coordinate bonding with the Lewis acid site of TiO2 surface are promising candidates as electron-accepting groups of new D-pi-A dye sensitizers for DSSCs.