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

摘要

Since the first report of dye-sensitized solar cells (DSSCs) by Gratzel and co-workers in 1991, DSSCs have received considerable attention because of their high incident solar light to electricity conversion efficiency and low cost of production. Recently, in order to increase power conversion efficiency, much research has focused on the development of new metal-free organic dye sensitizers. In particular, donor-acceptor π-conjugated (D-π-A) dyes with both the electron-donating (D) and electron-accepting (A) groups linked by a π-conjugated bridge that exhibits broad and intense absorption, are proposed as one of the most promising organic dye sensitizers. The spectral features of the d-π-A dyes are associated with the intramolecular charge transfer (ICT) excitation from the donor to the acceptor moiety of the dye, thus leading to efficient electron transfer from the excited dye through the acceptor moiety into the conduction band (CB) of TiO2. Most of the D-π-A dyes, such as coumarins, polyenes, thiophenes, and indolines, have dialkyl-amine or diphenylamine moieties as electron donor, and carboxylic acid, cyanoacrylic acid, or rhodanine-3-acetic acid moieties that act as electron acceptors as well as anchoring groups for attachment to a TiO2 surface.The carboxyl group enables good electronic communication between the dye and TiO2 by forming a strong ester linkage with the TiO2 surface. However, development of new d-π-A dyes for DSSCs is limited as long as the carboxyl group is employed as an anchor and electron acceptor.