A series of poly(arylene ethynylene) conjugated polyelectrolytes (CPEs) have been prepared, featuring a backbone consisting of a carboxylated bis(alkoxy)phenylene -1,4-ethynylene unit alternating with a second arylene ethynylene moiety (1,4-phenyl (PPE), 2,5-thienyl (TH), 2,5-(3,4-ethylenedioxy)thienyl (EDOT), and 1,4-benzo[2,1,3]- thiodiazole (BTD)).  Using these CPEs as sensitizer, nanocrystalline TiO₂ solar cells are fabricated and characterized.  The IPCE and power conversion efficiency indicate close correlation with the band gap energy.  In order to gain some insights into the kinetics for the involved charge transfer process, ns transient absorption spectroscopy are applied.

Chemical structures of variable band gag CPEs

Schematic structure of dye sensitized solar cell

Ref: (1) Zhao, X.; Pinto, M. R.; Hardison, L. M.; Mwaura, J.; Mueller, J.; Jiang, H.; Witker, D.; Kleiman, V. D.; Reynolds, J. R.; Schanze, K. S. "Variable Band Gap Poly(arylene ethynylene) Conjugated Polyelectrolytes." Macromolecules 2006, 39, 6355-6366.

(2) Mwaura, J. K.; Zhao, X.; Jiang, H.; Schanze, K. S.; Reynolds, J. R. "Spectral Broadening in Nanocrystalline TiO₂ Solar Cells Based on Poly(p-phenylene ethynylene) and Polythiophene Sensitizers." Chem. Mater. 2006, 18, 6109-6111.

(3) Taranekar, P.; Qiao, Q.; Jiang, H.; Ghiviriga, I.; Schanze, K. S.; Reynolds, J. R. "Hyperbranched Conjugated Polyelectrolyte Bilayers for Solar-Cell Applications." J. Am. Chem. Soc. 2007, 129, 8958-8959.