Dye-Sensitized Solar Cells Based on Donor-π-Acceptor Fluorescent Dyes with a Pyridine Ring as an Electron-Withdrawing-Injecting Anchoring Group

A new-type of donoracceptor p-conjugated (D-p-A) fluorescent dyes NI3NI8 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 NI3NI8 are greater than those for the conventional D-p-A dye sensitizers NI1 and NI2 with a carboxyl group as the electron-withdrawing anchoring group. The IR spectra of NI3NI8 adsorbed on TiO2 indicate the formation of coordinate bonds between the pyridine ring of dyes NI3NI8 and the Lewis acid sites (exposed Tin+ cations) of the TiO2 surface. This work demonstrates that the pyridine rings of D-p-A dye sensitizers that form a coordinate bond with the Lewis acid site of a TiO2 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-p-A dye sensitizers that form an ester linkage with the Bronsted acid sites of the TiO2 surface.